I know you're joking, but having a seperate phone exclusively for work stuff is actually great, specifically because it makes it easier to entirely seperate yourself from work. At my old job, I was given a work phone and it was the only phone number I used for all my work stuff. When I was at work, I would answer it, and outside of that it was off or on silent in my work bag. If they wanted me to answer outside of work hours, they had to pay me on-call rates. The same thing applied to group chats and other work-related stuff like that, (e.g. emails). It all went to that phone, and unless I was being paid to be contactable outside of work hours, I wouldn't be.

The only exception to that was my manager and a select few people who had my personal number for genuine emergencies, and if they used my personal number to contact me asking me about work, it was entirely at my discretion to respond and would mean I'd get on-call pay.

It also meant I could keep my work and personal accounts/apps/etc. completely seperate. If they asked me to download some random app, I could do it on the work phone without worrying about whether they would be able to access other data on my phone or anything like that. Whenever I needed a phone number for 2FA or whatever, I could use the work number and not worry about where exactly that number would end up or how it might be used. For example, I used my work number to register for a conference, and then for months afterwards I would get calls and texts from sales people. That was still slightly annoying, but it was much better than getting calls on my personal phone.

It also meant that when I left that job, I could just wipe that phone without having to worry about having personal data on there, because I never used it for anything except work stuff.

It does sound like Microsoft is asking their employees to pay for an iPhone which is a bit dodgy in my opinion, but I'd still probably take the opportunity to use it completely for work and keep my personal phone seperate. It's easy enough to get another number, and then when you leave that job you can cancel it and get a new number for the next job, cutting that link entirely.