I created a completely new consumer iCloud account and used that. I never did anything remotely "personal" on that machine, and after I left Apple I never used that iCloud account again. In fact I don't even remember my password for it.
I went so far as to carry two iPhones, one personal and the other "corporate," and I only ever used my "corporate" iPhone with Apple employee apps. I never even connected my personal phone to the campus WiFi; I used wireless data for that phone the entire time I was there.
That said, I don't recall ever being asked to merge my personal and work accounts. It's just that if you want to do any personal stuff with corp hardware, it's much more convenient to just use your personal Apple ID when you provision the hardware.
Unfortunately, this just seemed to lead to the most politically connected folks going remote and directors friends and favorite hires getting the perk.
At three trillion market cap, I guess they just realized it doesn't really matter if attrition shoots up and they'll always have enough people to fill the trenches. Lots and lots of people left around the same time.
Having left, I forgot what it was like to be able to focus on something other than Apple. Incredibly toxic atmosphere on the inside. I work at a fast-paced startup and still work on average 10/hours a week less than at Apple.
Maybe it was because I worked there only during the pandemic, but I never really felt the emotional impact of Apple's toxicity. I could of course tell it was there, and if I actually cared about getting promoted or getting higher pay, I might have felt more stressed.
For example, after pointing out some areas where I thought a proposal could be improved, from that point on I just wasn't ever invited to any more design or strategy meetings. It's like I was just cut out from everything because I had the audacity to criticize something from some senior schmuck with tenure, and I wouldn't grovel and kiss whoever's ass I needed to in order to be "allowed" in those meetings from that point forward.
In hindsight I was glad I torpedoed myself right off the bat after I joined. Not actually ever having to be around any of those people in meatspace probably helped, but it was really easy for me to sit in my office at home and plug away undisturbed on the pet projects that I felt were interesting and worthwhile. What I created actually was helpful, but it was totally designed, written, and delivered in a silo. I collected my salary and stock for a year, added Apple to my resume, and then hopped on to another company with higher comp and a much healthier culture.
Now at this new place, everyone is falling all over themselves to have me in their design and strategy meetings. <shrug> Fare thee well, Apple. I hardly knew ye.