ReactOS is not a solution - it's not even in Beta as yet. But the submitter was presumably asking about Linux in a generic sense - a free (as in beer, since Granny ain't gonna exercise her 4 GNU freedoms) UNIX-like OS, which one could install for her, and then never have to bother again.
So from that POV, granny may even be better off, since she won't have to worry about the drivers being liberated or unliberated or any of that stuff.
I was asking the second question. I know anything can (w/ the required time, effort & manpower) be ported anywhere. My question was - is OBSD already, or can it be made capable of running Linux (or FBSD) binaries OOTB (w/ appropriate support packages installed)? Yeah, VMs are a fallback option, but then an argument would be made that if one has to run FBSD or Linux VMs, why not run those OSs on the bare metal?
So does OBSD have the same variety of software available as do the others? I'm not talking about firewalls or other utilities - I'm thinking things like say, video editors, graphic editors, games and so on. Yeah, even if the latest doesn't run, it's fine - I just want to know that OBSD has a good collection of software.