If you think about it, any developer could have their account hacked and the attacker upload an APK that includes malware. Obtainium isn’t doing any malware scan or building from source or anything. If you are planning to just install from GitHub anyway, Obtainium should be a no-brainer. But I can see where might argue that having a middleman like F-Droid to validate APK integrity has some merits.
f-droid.org/docs/Security_Model/
Fair point. I guess it boils down to if you prefer speed of update (obtainium) or the extra checks f-droid has in place and if you continue to trust that f-droid’s stuff doesn’t get compromised.
It’s also worth mentioning f-droid’s workflow far from guarantees there’s nothing nefarious in a package. The bar looks to be passing virus total and then ensuring the provided apk matches source. If nobody reviews the source each time then every release could be the one that gets a nasty surprise.