I don’t think you should worry about the performance cost of calling a method on a component versus on an actor itself.
There is virtually no difference in performance cost unless you’re doing something like FindComponentByClass every time you call a method on it.
Epic recommends that new games be done with a major focus on Components instead of by cramming a lot of code onto a few classes. The entire LyraStarterGame framework is set up with that design in mind.
They have an inventory system in Lyra, I haven’t had time to investigate it yet, but it might be worth looking into if you haven’t already built something. Their system purportedly demonstrates best practices so it’s worth being aware of.