Needless to say several things stuck out but I was actually pretty surprised about their phone policy.
I was allowed to keep my phone the entire time and allowed to take pictures of everything except the control room and security related procedures, items, devices, etc. All the employee phones I saw were standard devices.
The asked us to avoid posting to social media but that was more of a consideration for why we were there. It didn’t seem to have anything to do with broader security concerns, etc.
All of that said you are accompanied by at least one escort the entire time, down to water breaks, bathroom visits (they wait for you outside), etc.
What they were most strict about was safety related issues that weren’t strictly nuclear related. For example, they take holding handrails incredibly seriously and if someone saw you taking a single step on stairs without holding a hand rail you’d (basically) get yelled at.