As much as i dislike google, chromebooks are perfect for anyone tech illiterate that just need a simple web browser that works. Every family member I’ve recommended a chromebook to has not needed additional tech support for it, which IMO, is a truly impressive accomplishment on google’s behalf.
Same thing for any other software, see if you can get it running in wine, and see what the alternatives are and try them out until you find a solution you like. You need to accept there may be change, and may need to experiment and hit up Google to find solutions, but solutions do exist.
From a quick Google search, i found about 4/5 potential open source options
FreeCAD would probably be what I try first, but it’s hardly the only option and seen some people complain that it feels archaic (but it’s FOSS). I’ve also seen draftsight recommended a few times, and it has a free trial but is not free.
Also apparently fusion360 has a web interface that may be usable.