(May edit later to add more specific thoughts on this) but yeah, the character Thancred (mostly likely the version of him from the Shadowbringers expansion onward) would make for a really good follower. he has a lot of voiced lines i think could be usable and is just overall a fun character, and i think he'd work well as a follower for Skyrim. throughout the game he uses a short sword, twin daggers, then a gunblade, which i saw earlier is already something on the Nexus, though might need a new model. he also has 3 distinctly different outfits if different versions of him strike your fancy, though his main look is a heavy trenchcoat with some armor underneath. also, his primary voice actor, Peter Bramhill, has a Cameo and you can probably get him to voice any line you want.
Edit 1: nevermind, his literal gunblade is already on the nexus https://www.nexusmods.com/skyrimspecialedition/mods/56720?tab=posts