I agree with most of your points but:

> No employer with a functional legal department would ever be okay with an employee using their personal devices for work (unless they have MDM software on the devices partition the work data).

This works the other way as well. While I (as an individual) have no legal departement, there is no way I'd ever be ok allowing work to touch anything on my devices, MDM or not.

My devices are mine, they will contain zero work stuff. Any device that workplace wants me to use for work, will be provided by the company, not me. I'll never allow any overlap.

(20 years ago I was at 100% overlap, no boundaries at all, but times have changed.)