I'm surprised that Apple is not considering opening up its own fabs. Tim Cook is all about vertical-integration and they have a mountain of cash that they could use to fund the initial startup capex.
Apple has very much been wanted absolute flexibility to adopt major technology changes so much they’ve tried hard to not be the sole customer of a supplier and deal with political ramifications (source: Apple in China/Patrick McGee)
Semiconductor manufacturing is not an incremental step for Apple. It's an entirely new kind of vertical. They do not have the resources to do this. If they could they would have by now.