Sure, that design work and firmware development is probably a miniscule part of their business in comparison to the scale of their App Store and other service revenues though. And Apple does no manufacturing at all, the screens come from Samsung and the phones are assembled by Foxconn.
Apple designs their own processors (now), specs/sources their components (e.g. screens), and then does all the integration engineering.
That's the bulk of device work.
Which isn't to say that semi manufacturing isn't hard, but is to say there's a lot of effort between a chip and a device.