Splitting phone and computer seems silly.
The Apple value pack comes mostly from brand value, deep ecosystem interactions, and being pretty much the only big corp ONLY focused on high end personal computing devices. Almost all their revenue is from B2C, their incentives are more aligned than most other big corps.
Any split to not actually harm the customers would be more focused on services such as apple card, icloud, the apple plus services (music,tv,…) etc.
Tbh, even EU mesures i think would be better if apple was instead forced to open the hardware (provide docs and bootloader, and no penalty for an user that takes advantage), rather than opening the OS or store. Not needing such openness on store and OS/core libs, actually allows apple to be more nimble and providing de better service (or bigger margins :( ), buto opnning hardware could actually give other OSs a chance, for once there could be a linux phone, as iphone has few hardware configs, and the device is very wide spread, 2 factors making it very attractive to devs (as example, check asahi linux, how quickly it became usable on a platform without docs)
This would play much more into “i bought this device i run wtv software I want” without restricting software vendors, Apple could keep the benefit of tight integration (that consumers like me like), but would have to provide the docs (and boot) for alternative OS to rise.