Edit#3: Yuzu and Citra have now been removed from the Flathub website, but are however still available via their flatpak commands:
flatpak install flathub org.yuzu_emu.yuzu
flatpak install flathub org.citra_emu.citra
For more context, A Flathub admin responded to someone on the Flathub Matrix channel saying that Yuzu won't be removed from Flathub completely until they "understand legal implications better"
There's a plethora of places. Github, Codeburg, Sourceforge. I'm definitely missing some others too. (There's also Gitlab but I don't really recommend Gitlab because of some recent decisions)