I would recommend on concentrating on setting up OP25 within an established Linux VM.
A running linux VM is a running linux VM, the environment is the same. Getting there can very wildly depending on the host hardware & software at play. If you are not going to include all the potential solutions, you could be doing the reader a disservice. You planning on covering bhyve, BSD jails or qemu? I don't think so, but if you concentrate on the installation after the user has done due dilligence and has a running linux VM/instance, you can save your self the trouble.
now I will say that if someone is running FreeBSD, and wishes to also run OP25, I would suspect that they would be able to implement it on their own. The baseline computer aptitude that is present in people who run alternative operating systems would make a hand-holding document like yours a bit reduntant, so you might not even find people like that utilizing your help. This doesn't mean you shouldn't do it, but maybe you should look at the big-options for the greatest number of mainstream users.
There are thousands of writeups for windows 10/11 (as well as win xp, vista, 7,8...) for getting a linux VM up and running, why repeat the work?