Considering a good chunk of the US population (15-30%?) is vocally "anti-BLM" - it is somewhat ballsy for a high-profile company to wear pro-BLM in their corporate messaging - I'm sure we've all seen people on Facebook vow to boycott Apple or other "liberal" organizations.
That doesn't really matter. Voluntary boycotts have little effect, and there probably no enough people who are so "anti-BLM" that they'd actually follow through on a boycott for Apple to notice.
A vocal segment might complaint on Apple, but where would they run to, Google's Android? Google is also pro BLM. All big tech are.
I don't think they will seize factories, as it just means every foreign company would look to exit. They will probably simply not allow them to sell their products in mainland and not give them any concessions.