TL;DR - never use company devices for personal materials. Create a separate, independent email strictly for work or your company email for all company devices, not your personal one.

I have a mobile device required for work, and my personal device.

No personal stuff goes on the work device. Photos, apps, logins, messaging, whatever. Zero. However, many of my colleagues use the device like, “Free mobile device, bro!” and load it up with everything they have on their personal device.

That is a horrible idea. The company device has its own cybersecurity app installed and managed by company servers that sees everything on your device, and should your device be used for something it shouldn’t, they don’t even have to take it from you to know what you did. They know when you did it, too. Watching movies or texting while driving? Reading a book or using social media while monitoring a system? If you crash the company car, or the system goes TU and they see you were fucking around with the company device instead of doing your job, you’re fucked. They see it all, it’s all regularly scanned, uploaded, screened, whatever. They just don’t bother to look unless they need to. Already had a couple people fired for illegal material on their devices.