no, there are only open source modifications of the closed source client.

I know this doesn’t answer your question, but using a 3rd party client or modifying the discord client is technically against the discord TOS. They don’t really enforce it unless you’re selfbotting or whatever, but there have been cases where people got banned from 3rd party clients because of a bug within the client that caused apparently bot-like behavior.

The only FOSS alternative is Matrix. Discord itself cannot/shouldn’t be used with an alternative client because it’s against the Discord TOS.