When I worked at Google over 5 years ago, mobile device options for accessing company accounts were a company-provided and company-owned device with a company-paid phone bill, a personal device with company-provided mobile device management (and sometimes cell phone bill expensing if you for example had on-call duties), a personal device with only limited browser-based work account access, and no account access via mobile.
The first of these could sometimes have implications for ownership of personal projects created using the device, which was one of many reasons I picked the second option, but it was absolutely permitted at least for any case where the company cared about you having mobile account access.