This loony bullshit is why tankies go full useful idiot and parrot shit most of them know isn’t true. The right-wing disinfo about Tianamen square - or any other communist atrocity - is so widespread. Tankies think that the most ultra counter-narrative will somehow combat that even if its just as loony.
People seem to be misunderstanding your question. It doesn’t sound like you are lacking educational resources to learn C# but a lack of reasons. It sounds like you have been learning by getting you’re hands dirty with foss software.
C# is a sort of “enterprise-grade language” like Java. It’s meant for large applications developed by one or more teams for almost exclusively commercial purposes. If you want to learn it, deeply, you’ll have to come up with an excuse to write in it. A game is probably the best choice for this. Then learning c# is learning how to make your game.
If you’re looking for open source C# software to hack on you can try anything from the *arr stack. (Sonarr, radarr, lidarr).