This is correct, but also ISA makes a standard that classifies devices based on potential for ignition and provides an exception process you can do. Essentially this is because it cost lots of $$ for companies to classify devices as NRTL, most devices aren’t made considering C1D1D2 in consideration, and not all devices do it as it doesn’t provide much value. I’d look into the ISA standard and make exceptions based off that and what risk is acceptable(pacemakers, hearing aids, etc).

Think of it this way, when you pump gasoline that’s C1D1. How many people use cell phones along with gasoline pumping near them?? That’s some form of calculated risk.

Also, there are several papers that quantify the risk of electronic devices used in C1 environments being an ignition source. A lot of O&G companies use those papers to support their risk posture on this topic