Totally agree with everything you said, but I really appreciate that you can access ALL of the settings from the android app. It drove me up the wall that you can't manage filters and labels and stuff from the gmail app.
Wish they had https://www.claws-mail.org/ for iOS and Android. I remember K9 for Android used to be decent back in the day when Android was on the G1 and OG Droid, no idea if it’s even still around.
This. It's actually one of the things that drove me away from ProtonMail and into the arms of FastMail (for emails that don't need quite that level of security, i.e. most).
For a browser wrapper app though, they've done much better than any other I've seen. It's just slightly slow on notifications, to load, and isn't usable offline.
Outlook for iOS is surprisingly good.