Ádám

That could be done after the user enters both the email/username and password

Edit: sorry, I think I misunderstood what you said, but if someone is using something like “sign in with google”, we’ve had separate buttons for that for ages.

I don’t think there’s any reason not to use it. It’s carefully curated, I haven’t come across any malware on it (of course that doesn’t apply if you add random repositories). Personally, whenever I need to download an app, F-Droid is the first place I check.