Hello! Is there any reason why you might not use the app binary/files from their release page? (latest 1.8.86). I was also trying to run brave from a toolbox, and while I did have a lot of success, the audio was not as reliable as I wanted. I found a post on another thread (THANK YOU @kcalvelli) that made lots of sense to me… so while it is obviously a much more manual process (for me) to check for and “install” updates, the integration is TIGHT with SilverBlue and feels akin to layering the brave package onto the OS.
So maybe, if anything, use Ansible to check for, download, and unzip new stable Brave releases for you 
I sure hope this is useful information!