I don’t know for sure, but I suspect a lot of the work is spent sussing out weird edge cases with different binaries. This is tedious, thankless work, but it is necessary to have true Windows compatibility.
Wine and Proton have gotten so good that I don’t bother even checking compatibility before I buy games. The game will likely run just as well or better than on Windows and it is so consistently good that it’s not worth the small effort to check ProtonDB.
I do wish that they would get Office 2024 working on Wine. This isn’t a dig at the Wine devs at all, I am sure that it’s a very hard problem, but if I can get that then I will have even more ammunition to get my parents to drop windows entirely.
If it doesn’t say Microsoft Office on there, they will say it’s worse. Objectivity has little to do with it.
In a bit of fairness, my dad makes extremely liberal use of the VBA in Excel, and I am not sure how compatible OnlyOffice is for that.
I haven't ruled that out yet. I am planning on trying to convince them on this next time they ask me for tech support.
[1] I'll say it again; if anyone here works on Windows Update, please consider getting out of the software game and maybe consider a job in the exciting world of janitorial or food service, because you are exceedingly bad at the whole "software thing" and you should be ashamed of yourself and how much damage you have cost the entire world with your utterly incompetent software.