I used OS/2 and to say that I was annoyed at Microsoft's antics at the time would be a gross understatement. These days I use mainly Linux but I've legacy machines that still run Windows 7 which I've vowed never to upgrade for obvious reasons.
Whilst there are Linux workarounds for most Windows situations, Wine,
alternative software, LibreOffice etc., often these can be messy or inconvenient to implement (in my case they often occur when longtime Windows users ask me to upgrade their Windows machines and they don't want Win 10 or 11 installed on them.
Here, the switch to Linux is often a step too far (and often they've legacy Windows apps that won't run under Wine—for instance, certain Windows CAD programs that have no Linux version (and their dongles only complicate matters)).
This brings me to alternatives: Acra Noae/OS/2 is too old and unsuitable, this only leaves ReactOS, which is a project going nowhere—its development speed makes a snail look like a hare (why there's so little interest in this project is odd given that the payoff would be great if it were successful).
The question I've never had answered successfully is why after all these years hasn't there been a successful clone of Windows. And by that I don't mean a clone of the grossly over-bloated 7GB kind currently availale from MS—the outrageous size of these behemoths is one of the reasons why users like me want a small streamlined alternative O/S.
ReactOS would fit the bill re small size and basic features but it just doesn't work and probably never will. Nevertheless sufficient of it exists to prove the concept is actually feasible—especially, if the principal aim was limited to just building a basic utilitarian Win API- compatible OS with a basic CUA-type GUI. For many of us, a minimalist GUI-based file loader/task switcher is all that we need (the O/S I envisage would be more like OS/2, as such, given its limited features, it'd hardly even qualify as a Windows clone).
It's perplexing that a viable alternative product hasn't emerged in recent decades and I'm not totally convinced that Microsoft's saber-rattling over copyright etc. is the full reason it hasn't.
MS hasn't made any serious moves to close down ReactOS, perhaps because there aren't any copyright breaches serious enough to prosecute, or it's worried about antitrust/monopoly action being launched against it—or that it doesn't need the PR problem of being accused again of being a bully, or that it thinks that ReactOS is too insignificant and too late to worry about—or it' a combination of these factors.
MS would likely have little difficulty in scaring off 'respectable' Western money for development but I doubt that the same pressure would be just as effective in Russia or China—remember the publicly ReactOS received when it was demonstrated to Putin several decades ago? It was quite a splash.
The question is why those countries didn't take that opportunity and run with it. The economic and strategic advantages seem obvious, so does the kudos that they would've gained. Clearly, I'm missing some important factor here.
Re OS/2, it would be interesting to know details of the agreement between IBM and Microsoft and what percentage of the code each contributed to the project. If IBM did most of the development then perhaps the MS code could have been stripped out but I'd suspect the reverse was the case.