I myself mostly use the following features from Keybase: Chat, KBFS, Git repositories and encrypting messages sent out-of-band via PGP in Keybase (and the various cryptographic tools [signing, validation etc])
What alternatives have the features outlined above, but are ideally either FOSS or at least not run by a for-profit company? I mainly used Keybase to make using those features easier, so please don't suggest the cli of gnupgp (or similar) as alternatives.