I gather ReactOS builds upon the work for WINE and other open-source Windows-compatibility libraries - nothing wrong with that, but it isn't as impressive as it sounds - not that ReactOS as-a-whole isn't impressive as it is.
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Dirty rumour + speculation time: I understand that, to an extent, ReactOS is supported by the Russian government to ensure they have options for running their IT systems in the event of US or NATO-led sanctions which would prohibit service and support from Microsoft corporation. Ordinarily I wouldn't be concerned (geopolitics, yey) but given Putin's current direction... I hope ReactOS is getting suitably security audited...
If that's Russia's backup plan then it's severely underfunded. I'm sure Russia could hire a couple of capable software engineers/reverse engineering experts to contribute to the project (just as the US Naval Research Laboratory employed people working on TOR). But if Russia is doing that, then clearly not enough to bring ReactOS to a production-ready level within the next decade.
Given current US direction, I hope ReactOS is getting suitably security audited...
To be clear, I don't know what Biden is up to but any country big enough sure have secret services making sure their country stays in the game. That's just part of history.
Now, as an individual, I'd be very happy to have a clean OS. But, considering the difficulty/practical impossibility to make my own audit, well, in the end, I have to trust someone...