No, as far as I know, at Apple, this is strict - you cannot contribute to OSS, period. Not from your own equipment nor your friend's, not even during a vacation. It may cost you your job. Of course, it's not universal for every team, but on teams I know a few people - that's what I heard. Some companies just don't give a single fuck of what you want or need, or where your ideals lie.

I suspect it's not just Apple, I have "lost" so many good GitHub friends - incredible artisans and contributors, they've gotten well-payed jobs and then suddenly... not a single green dot on the wall since. That's sad. I hope they're getting paid more than enough.

Every programming job I've ever had, I've been required at certain points to make open source contributions. Granted, that was always "we have an issue with this OSS library/software we use, your task this sprint is to get that fixed".

I won't say never, but it would take an exceedingly large comp plan for me to sign paperwork forbidding me from working on hobby projects. That's pretty orwellian. I'm not allowed to work on hobby projects on company time, but that seems fair, since I also can't spend work hours doing non-programming hobbies either.