Not sure how Peergos is a relevant alternative to Keybase? Maybe you're just thinking of the file sharing aspect of Keybase?
Keybase as it's core was that it's a key directory that's publicly auditable. Everyone could verify the chain of verification of each other in Keybase. On top of that infrastructure, files and chat was added.
Peergos doesn't seem to show any chains or in fact auditable information at all. You can add/remove friends that is supposedly cryptographically verified, but there is no information about it, nor is there any information about where the data is actually stored, how you can get it to your local machine, how to re-verify the claims, how to add devices that have access.
There is a public append-only merkle-tree with all identities published in it in an analogous way to certificate transparency. When you add a friend you are looking them up in this tree and then storing their public key chain in your own (private) storage in a tofu manner (then any key changes they make are verified against your local copy).
You can also verify keys in person using the same protocol as Signal (via QR codes or number groups).
There are no private keys stored on any devices, so adding devices is not a thing. It is a pure capability based system.
Unlike keybase, we are fully open source and self-hostable.
