With WoW Classic out, maybe there are others playing WoW on Solus. (You can do so with Lutris). Be sure to follow the instructions linked in the lutris description here. The instructions include a link to further instructions for Blizzard App which there are instructions for Solus.
But you will find that to manage your addons most use Curseforge and the Twitch Desktop App to update/manage them. Not only is Twitch Desktop App not open-source, but the addon-managing part of the app isn't part of the linux Twitch Desktop App.
So I found wowman on github which can manage and update your addons from Curseforge and wowinterface.com. It has worked great for me. Just be sure to follow first time instructions in the README which I will paste here for convenience:
First time usage:
select your "Addons" directory (/path/to/WoW/retail/Interface/Addons)
from the Addons menu select Re-install all to automatically re-install all matching addons
addons that are not automatically matched can be searched for and installed from the search tab
finally, addons can be deleted by selecting them, right-clicking, and selecting delete. Multiple addons can be selected and removed at once.
Afterwards, simply use the Update all button to update all addons with new versions available. Addons with new versions available will be highlighted.
Also, be sure to select the proper WoW version you are using (classic/retail) in the wowman interface.