The Mail app looked great, but I would hardly call it perfect. It constantly failed to notify me of new emails or calendar events, and I know I'm not alone in that.
Project Treble and GSIs solve a lot of the intercompatibility issues. Of course, Treble doesn't help if your device wasn't originally Android, or came out before Treble existed.
Stars could be from people who used to use it and no longer do, or who planned to try it out but never got around to it.
GitHub forks are kind of a meaningless statistic in my experience. So many of them are from people accidentally forking the repo and just never deleting their fork, or from spam accounts that fork random repos to make PRs with random content.
I need to release an update to refresh the supported domains soon, but I made an app that does the work of maintaining the giant list of possible domains and helps you set it as the default for all of them.
Not every client is supported, but there are a few options.
They're women