I think Odyssee is open source. Not sure if it's 100% free and they are fighting the Sec lawsuits so not sure if they can sustain themselves.
Discussion
Odysee is just a client for the LBRY protocol. It is definitely free both as a creator and a user. Their API is open (they even claim that it's not an api, that it's a protocol, gotta dig around more to verify it's not just marketing bs)
They however rely on their own shitcoin LBC and it's underlying blockchain.