> What isn't clear to me is whether Win32 is still technically a viable choice for "modern" Windows 10/11 development. In other words, could you submit a Win32 app to the Microsoft Store, if that was something you felt like doing?

I believe so, although originally the store required other toolkits, they changed thier mind.

That said, I don't think it's very important for windows programs to come from the microsoft store... the limitations are not worth the market, especially since the store is unreliable: at least in my experience, the installation can get messed up and it won't self repair, and then you can't install new software... Why would you want to support that, when you could just provide a downloadable installer and license keys? (And tell people the sequence to escape store only mode)