It was unfortunate, but not unexpected. Neo Launcher is a decent alternative, though it's not quite on par with Nova, and their development has been very slow the last year. Benefit of GrapheneOS, I can just disable Nova's network access, so I don't really have to compromise here thankfully.
Not yet. Nova Launcher 8 is the problem version and it's still in beta. If you're still using version 7, particularly 7.0.57, then it's the version from before the buyout and it's clean. It's suspected they turned some analytics on with 7.0.58, but even that still looks clean to me. That is the only update they've pushed since the buyout.
My guess is they didn't want to fuck with the current version, they just wanted to devote their focus to getting all the tracking shit into the upcoming major release.
If you disable auto updates now, you'll probably be fine until it stops working
I quite like Neo/Omega launcher, it's probably the best FOSS launcher I've found.
their development has been very slow the last year
This is the painful part. There are regressions that have been introduced which have sat their for years, and I've got no idea if they'll ever be fixed. But such is the open source way, they owe me nothing and are still providing a generally good experience for free!