Okay there was actually one more gosuku bromances I remembered from Boys Don't Cry, a stoner skfs fic. I love it a lot tho it's incomplete and hasn't been updated in a while 🥲
https://archiveofourown.org/works/41694066/chapters/104590551
Then there's Run the Route, star college football sukuna, still ongoing
https://archiveofourown.org/works/55460278/chapters/140730934
Then there's Kings Gambit, long skfs omegaverse, gojo and sukuna are ceo/Yakuza bosses that have been friends since they were young, idk if you consider it bromance but they are best friends
https://archiveofourown.org/works/29624100/chapters/72826773
oh! And New Skin! Idk if they're bestie besties but they are at the very least friends and rivals with their bands
https://archiveofourown.org/works/48327670/chapters/121886674