I thought they were using matrix
That latest version of nostr:npub1uq70uqgas9pyhds2zt57kr9se8rg3s68ztphjnq82ts8rzeknmeql7u0c2 is powered by Nostr. I didn't know this. Fedi accounts are Nostr npubs. Fedi also includes a NIP-07 signing extension allowing you to browse and use the Other Stuff of Nostr with ease. I saw a handful of Nostr apps included on this "apps tab". They just work. You can also export your private key to use the key in other apps. And soon, you'll be able to import your existing private key. Mind is blown. Super bullish.
Discussion
When showing me, Cody mentioned that they were originally using Matrix but have since implemented Nostr.
Clarification. They're using Matrix for group chats and DMs, but with NIP-17 merged they can move to Nostr DMs. But right now it's just the npub identities and NIP-07 signer for apps.