WebCord is an “alternative client” for Discord, although it’s just running the Discord webpage in electron. Recently it updated its electron version so it supports sharing audio as well as video.
I tried it out today on mint (x11, pulseaudio) and it works flawlessly.
I would caution anyone using a client mod like that, since it is technically against Discord’s terms of service. To be fair I’ve never heard of them banning anyone for that, but it’s worth noting. Webcord is generally a much safer option.