I’m sure they would call OSX a BSD replacement

No they wouldn’t. That’s Linux, among other things, because when it was gaining popularity, BSDs were defending from lawsuits and rewriting litigious parts belonging to AT&T (that is, preserved from original Unix sources).

Right now the biggest wall from wider consumer adoption of Linux. Is honestly, simply the lack of systems offered to consumers with it. Outside of a few games with kernel level anti cheat. Or highly proprietary specialized softwares. There’s very little that you cannot currently do on Linux that you can do on Windows.

No. Actually no, that’s not the biggest wall.

Under modern Windows you can run software compiled for Windows XP. Under Linux you’ll have a lot of sex with your system before achieving that kind of backwards compatibility.

Since you mentioned BSDs, and they are similar to Linux in daily usage, with FreeBSD you may install compat4x, compat5x and so on packages and run rather old binaries. FreeBSD version of Opera browser (yep, they made a FreeBSD version), which was a binary from Opera Software, didn’t receive an update since 2013 and till 2021 and it was in working condition.

This wall for your typical Windows user is hard to describe. They are doing something the only normal way they understand and are told that they are holding it wrong. Say, they install a package for the previous major version of their distribution. Or just try to run some binary downloaded from somewhere and it tells them angry things about libc version and possibly other libraries.

Also the “advanced” things under Linux are not usable for many people, and the “user-friendly” things are complex and buggy.

Of course, Windows users also would really like to use their familiar Windows applications, but that’s not as important, Wine solves a lot of it.