> The fundamental question is whether Apple should be able to sell products with lock in.
Unpopular opinion in these parts, but I think yes, they should be able to (continue) to sell products with lock in.
Where Apple should get in trouble is specifically locking others out, rather than locking their own stuff in. If Apple wants to make a smartwatch that only works with iPhones, fine. What they shouldn't be able to do is block (either intentionally or via undocumented/private APIs and TOS violations) third parties from making a smartwatch for iPhone that can compete on the same playing field as the Apple Watch, with access to all of the same features.
Same goes for all tech companies. If you want to lock-in your own first party products, fine, but you absolutely should not be allowed to lock-out others.