It's another Ecash protocol, somewhat similar to Cashu, but with a different trust model that is actually getting pretty interesting even for a pretty solid skeptic about custodial solutions, thanks to using a distributed trust model that, while smaller, isn't terribly unlike the trust solution Bitcoin itself uses.
is a great recent look at the state of it if podcasts are your thing. Been seeing a fair bit of adoption in Africa.
And just be aware, there's Fedi, and there's Fedimint, and they're related, but not the same.
is a good place to look at direct information if you're looking.

Fountain: Podcasts & Music
What Bitcoin Did • Rebuilding the World’s Financial System with Bitcoin | Obi Nwosu • Watch on Fountain
Obi Nwosu is the CEO and co-founder of Fedi.
In this episode, Obi explains how Bitcoin can uplift billions by creating new forms of community-based...

Fedi — A Bitcoin wallet featuring privacy, chat, community, and more. Powered by Fedimint.
Fedi is the privacy-first Bitcoin app that lets your community send money, chat securely, and customize with Mini Apps.