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.
Vendetta
While Vendetta may still work for now, the devs have officially stopped working on Vendetta as of February 6th
Shit, i didn’t know that. I just read it now because of your reply. I hope someone fork the repo and maintain it
Someone is working on it https://github.com/revenge-mod/Revenge
“purple-discord” is the only free software Discord client I know about. It is a plugin for Pidgin and other libpurple based messengers such as Bitlbee.
“rdircd” the “reliable Discord client IRC daemon” might be an alternative but I’ve never used it.
Neither of these run out of the box on mobile but you can run them on a server you control, or maybe you could run them under Termux (have never tried this).
You can also use a Matrix or IRC bridge if you control the Discord “server.”
I don’t count client mods or web wrappers as they are fundamentally coupled to the proprietary client.
