I'm agreeing with your second PhD consultant and Buffy generally.
Firstly, I'd ask you why (really) are you thinking of doing a PhD in this area ? A PhD is a license to teach in the area of your research topic as well in those areas of technology that support it. If you like the idea of working in an academic environment then a PhD is a must. If you are simply seeking a higher qualification, or want to gain specialist expertise and then return to the commercial/consultancy world then I do not think a PhD would be the way to go. I say this because the human environment in academic life with their invisible social hierarchies and extreme individualism will probably not suit you. Discuss this aspect with someone who knows your nature well.
But let's say that you decide to do a PhD.
Whatever topic you select on immersive technology you'll always have to do things like background introduction to immersive tech and extensive literature search on your own topic of choice. That will cover current state and current taxonomies. (I doubt if there's any sense in your creating taxonomies for a developing field, especially where preferred academic and commercial lines of enquiry may not yet have been fixed - that's someone else's job.)
These are things that you'll get no marks for - though you will be denied a PhD if these parts of your thesis are deemed inadequate!
Secondly, your spending time in your thesis speculating on the commercial attraction of this technology or even of your own particular study is a waste. Like many of us starting out on a PhD, you don't have a clear idea on what a doctoral thesis is. A doctoral thesis is an original, independent and substantive addition to the existing knowledge in that particular field of study that is deemed worthy of publication in peer-reviewed journals. It need not have any social or commercial application whatsoever, at least not directly.
Of course, commercial application may be very important to you. Yet from the point of view of research coherency you must make a decision on what exactly you are concentrating your efforts on and stick with that. Otherwise you may be changing the direction of the study too many times to make any serious inroad into any aspect of imm tech.
So your idea of melding together existing knowledge and designing & implementing some solution to an as-yet unidentified problem is not a runner. You have to define your design & implement objective. Then you have to find an academic supervisor who is genuinely interested in supervising it - and with whom you can truly mix minds.
Then there is the funding question and then the real hard work, days & evenings, often Saturday and Sunday, summer and winter. You'll be surrounded with 20-30 other self-centered researchers like yourself and without an academic leadership that insists on it, cooperation will be minimal. So don't just decide after seeing an agreeable supervisor. Look at the others in the research group too. You are going to get to know more about them than you ever want to - and they will see you equally clearly. Your social life will be rather poor while doing your academic research unless you are at ease with the type of people in university, their foibles and prejudices. All existing relationships will take a hit - not just because of the relative lack of money but the unreasonable hours, the deep thinking alone in the evenings and the mood swings that go with successes and failures. If you have college work to do like demonstrating/teaching that will be another drain - unless this is something that you actually enjoy and are good at.
If you aspire to an academic career, you'll take all this on. But if any of it isn't for you, then just look for a job where you can learn about this technology and have scope to do your own work on it.
Either way, good luck to you.