My biggest obstacle to de-Googling is the GBoard keyboard of all things. There's really no good open source alternative that even comes close.
[1]: https://keyboard.futo.org/
[2]: I never investigated this, so I always assumed that GBoard predicted what key I wanted to press when close to two letters. With FOSS keyboards, with a physically identical layout, I tended to make way more mistakes.
it's also not as good at "recovering" from typing too many letters (Gboard sometimes adequately completes with likely shorter words)
UnifiedPush, F-Droid, a GMaps webview (arguably cheating, but I'm not RMS), NewPipe or Invidious are all good-enough alternatives, but I remember struggling to find a keyboard that felt right when I was using a Pixel 2 for a fortnight.
I think I went with the oldest Fleksy or Minuum APK I could find (from a reputable source), as they were fine without GApps.
Though I'd also like to call out the fact that AOSP has talkback, the accessibility service built-in, but there's no AOSP TTS engine to use it with. This is especially noticable when trying to use any spoken directions in OSMAnd, as it requires a TTS engine to use that function.
The only reason it's not the dumbest thing about Google's stewardship of AOSP is that I'm not sight impaired - as it stands, the multi-trillion-dollar corporation ripping out the built-in SIP client in their phone OS takes that prize