The VOIDRUNNER'S CODEX is LIVE! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
I'm actually glad it's being sold for purchase. IIRC, this was originally a backer only reward type deal when the developers launched the Kickstarter to secure funding for the video game version of Crown of Solasta.
IIRC, both Adventures in Middle-Earth 5E and Beowulf:Age of Heroes pretty much does this with their INT skills in regard to like History/Arcane/ETC minus the Disadvantage (respectively as Lore/Legends).
So,ya that would work too.
Honestly, I think the Warlock makes for a pretty fine Gish, or at least a starting point for one, in 5E. And with the updated Pact of The Blade, even more so.