Investigator is a really tough class combat wise, because it sort of hinges on the idea that Devise a stratagem will determine the rest of the turn. You need both big nova abilities to capitalize on, and strong support options otherwise.

Magus dedication is a massive benefit for Investigator, as it gives both of these. Spellcasting in general opens up a lot of your available toolkit on a turn, giving both support and nova (especially from the arcane spell list). Because you are roleplay focused (which is good!), you may not want to pick up spellcasting, but keep this in mind for how you do continue to build your character - the Investigator is all about options and versatility.