Tyranny of Dragons (Hoard of the Dragon Queen plus The Rise of Tiamat) was the first full-length campaign I ran for my fifth-edition Dungeons & Dragons group, after putting them through The Lost Mine of Phandelver. It was the right campaign for the moment, and its linear nature and geographic jumping around made it easy to insert character-specific side quests, which I appreciated. It also had many flaws, though, and a big one is that the dragon cultists just weren’t that interesting or memorable as opponents. (There’s also all of “Mission to Thay,” chapter 8 of Rise of Tiamat, which … whoo, boy, don’t get me started on that.)
Might the insertion of some dragon followers or dragonborn champions from Fizban’s Treasury of Dragons have livened up Tyranny? Maybe, but not without some fiddling.