Merely asking to see your data, and expecting open scientific work, is not at all inappropriate, and nothing you have described so far amounts to anything untoward by this VP. You are certainly right to tread carefully, but you may be getting ahead of yourself in regard to concerns about "pressure" and "retaliation". Indeed, I would go further and say that it is desirable that scientific researchers should generally be under some pressure to make the data for their work available either to the public or other researchers. (I am also sceptical of characterising legal action as "retaliation"; see further commentary below.**)
You will have to decide if you intend to make your data public, or make it available to other researchers, etc. If you are withholding access then you should have a good reason for this, and it should be communicated to people who seek access to the data. When you publish your research, the journal might also impose requirements on you in respect to data availability. Whatever your decision, it is certainly a bad look if you refuse to give access to your data to other researchers on the basis that they take an opposing view of the efficacy of the research to your own (or on the basis that they have interests that conflict with yours). Ideally, you will be able to formulate a reasonable way for other researchers to get access to your data, perhaps subject to reasonable restrictions that do not constrain their ability to oppose your own findings. Perhaps you can even negotiate some data-sharing arrangement where each organisation provides a quid pro quo in terms of data access.
In any case, by your own description, you have "low confidence" in the evidence adverse to the device. Presumably that assessment will be incorporated into your published work on the topic, so that the reader is aware both of the direction and strength of the evidence. You will need to decide whether the evidence is strong enough to assert a conclusion at all, or if it is so weak that it would be irresponsible to make a clear conclusion on the device. The fact that you have low confidence in your result does not necessarily mean that you cannot state it, but you should be careful to impose appropriate caution and caveats.
I note that the company asked for access to your manuscript prior to publication, and you have refused this on the basis that you think it might raise a suspicion of collusion by readers. That is not a fanciful objection, but it is unlikely to occur in a context where you are making findings that are adverse to their product. In any case, it is also worth noting that it is handy to have a dissenting pair of eyes review your work prior to publication, since they will likely push back on anything in the manuscript that is in error or is weak. This is also handy if you are concerned about legal action, since it will give you an opportunity to see what, if any, objections the company raises against your work pre-publication. If the matter proceeds to legal action later, it will be hard for the company to raise new objections if they have already been given an opportunity for feedback and review prior to publication of the work. Consequently one thing to consider here is whether it would be worth having a member of this company provide a referee report prior to or during peer review. (You would not normally need to give data access for this to occur.) The advantage of this is that you then get pre-publication information on what they object to, and you can make changes if you think that any of their criticisms have merit. Manuscripts do not usually disclose the identities of referees, but in this case you might ask the journal editor for guidance.
In terms of possible legal action by this company, that is something you should speak to a lawyer about. In principle, a publication giving an adverse review of a product could amount to defamation, product disparagement, or a related tort. If your research work is negligent then it could also amount to a tort of negligence. A lawyer will be able to advise you more specifically on these matters, but one thing to bear in mind here is that one element of the tort of product disparagement is knowledge of falsity of an assertion or "reckless disregard" of its truth or falsity. The latter will be much easier for the company to prove if they can show that they tried to talk to you about the research (to raise objections) and you refused to listen to them or communicate with them at all.
On characterising legal action as "retaliation": One thing that bothers me a great deal when I see these kinds of reactions (as in your post) is this tendency to characterise legal action as "retaliation", in the sense often used in procedures to prevent victimisation of complainants. This type of characterisation smacks of bad faith --- if the taking of legal action is "retaliation", in the sense used in procedures for victimisation of complainants, then the speaker is implicitly saying that other people/companies should not have any legal rights in regard to their own conduct. Of course, some laws and legal procedures are indeed abused, but some laws exist as genuine protections of rights, and it is perfectly reasonable for people/companies to avail themselves of those protections when appropriate.
Aside from being quite sociopathic in its own right, such talk is also potentially legally dangerous, insofar as it gives evidence of bad faith and reckless disregard for the rights of others (which can be elements of torts on these matters). If you start out these types of negotiations by considering the possibility of legal action by the other side as "retaliation" you essentially have a total disregard for them having any legal rights in relation to your own conduct. You are effectively saying: I should be above the law. Ask yourself, if the shoe was on the other foot, and someone was thinking about publishing commentary that was adverse to your skills as a researcher, your professional competence, etc., would you like to be treated this way? Wouldn't you be glad that you have some legal protections? Would you consider the exercise of your valid legal protections (by taking legal action if necessary) to be a form of "retaliation"? (To take a more extreme example: If a rape-victim reports their rapist to the police, and maybe also sues them in civil court, would you characterise that as "retaliation"?)
I don't intend for this to be a severe criticism, because I think some people just use this term "retaliation" rather flippantly, because they get extremely defensive and nervous at the thought of legal processes, and they let this override any real assessment of the implications. A much better approach in these matters is to go into the matter with a genuine respect for the rights of the other party, and give genuine consideration to whether or not your actions are lawful and fair to them. Instead of regarding legal action as "retaliation" against you for your (presumed) perfect conduct, regard it as a thing that might happen to resolve a dispute by the ruling of a third-party (the court) if that becomes necessary. Give proper consideration to the fact that you might do something wrong if you are not careful, and seek information that will ensure that you do not do something wrong. Don't be afraid of legal action per se --- be afraid of doing something that breaches the rights of another party.
