If Samsung (or any other fab) were to make Apple chips they wouldn’t learn anything that a good microscope couldn’t already tell them.
Samsung still makes the displays and the cameras for most iPhones. They continued to do business even while engaged in legal action. That they are still competitors wont stop them doing business when it suits them. Business doesn’t care about pride or loyalty; only money.
I believe just locking at a chip, does not enable you to to make such a chip, otherwise china would not be behind.
TSMC already makes them in their labs. They could tweak a few things, claim it is novel and just sell to the competition. (Apple would fight back of course with all they have and TSMC reputation would take damage)