There are reasons both higher end manufacturers mentioned do not allow floating systems. I am the same way. 3/4 inch engineered but only glue down or nail down. You'll find somebody that says it's okay. Buyer beware on that.

OSB? What's the rating or the specs. Check for printed information on the sheets. Older than 30 years?

Yes unfortunately we are a 1985 build, so no specs or sheets on it. Can we glue down? Any suggestions?

It could be glued direct, but I would get some local professional opinions on the type and condition of the OSB including thickness and floor joist spacing.

You might be better off in the long run to change the subfloor and IMO if you keep the subfloor then why not do LVP that is amost always installed floating

Thank you, I was concerned the LVP may fade, but perhaps the newer brands don't?