I've done some work at my industry research internship that has led to a draft of a paper. I am currently applying to PhD programs, and the company at which I interned has a lengthy internal review process which will result in an inability to submit the paper to either a publication venue or a preprint server until after most of my applications are due. The abstract has been approved by internal review and submitted to a journal, but I will be unable to share the paper in time.
Is there a best practice for demonstrating that I've done research that has led to a paper, while also not yet having published the paper someplace due to these constraints? My supervisor has agreed to write a letter of recommendation on my behalf, so I suppose they can write about this, but I'm wondering if I should perhaps add a section on my CV to accommodate for this situation, or address it in my personal statement. I'd appreciate any and all suggestions, thanks!