If you don't mind a hosted version, you could try https://hosting.coracle.social. It's not too bad, but definitely requires some technical ability. For a relay that doesn't have blossom, flotilla will use your top personal blossom server to upload stuff (and will do the same for other users as well). However, these uploads will be encrypted, with the key included in the message you send, so they will be as private as the messages in the chat