Yeah it is possible to install universe on a brawl but not in the vc version of brawl. Download a normal version of brawl in your fat32 usb and then you just have to use ocarina cheats on your usb loader gx to get universe work on your brawl. This is the method what I used to get universe work...
I'm gonna buy another Series X, but can't decide if I should wait till the Xbox June event (maybe they get discounted) or just buy now. What do you guys think?