Thank you all so much for very valuable feedback.
Yes, so I'm a solo founder. I have released an app in the AppStore, and considering releasing more. I thought an LLC or some other legal structure would be useful for legal protection, tax deductions (if the app gets some traction, I'll start paying a considerable amount in server fees), and brand name.
It seems to me that for now, it would make sense to just do it online. If down the road I want (and can) hire employees or raise funding, I'll have to convert it to a C-corp.
One more thing: it seems that incorporating in DE makes sense only for a C-corp. So for the LLC, should I create it in my state (CA)?