There's a number of firmware jobs on their website at the moment. All of them ask for C or C++ experience - I haven't seen anything that's asking for Rust or Embedded Swift experience.
> One major development snag involves the software used to power the modem, some of which was acquired from Intel. The Intel code wasn’t up to the task, and most of it had to be rewritten from scratch, people involved in the project said. As Apple engineers sought to add new features, existing capabilities would break, and the modem wouldn’t work properly.
E.g.: https://jobs.apple.com/en-us/details/200579953/embedded-5g-4...