I’m not sure if I’m missing how to do this, but if not I’ll get this moved (or re-post?) into the feature requests forum. I would love it if pressure were handled similarly to temperature, where the units are auto-converted (I think that happens in the front end?) based on the configured unit system … but I would also love it if there were a way to override the unit system option for a particular sensor. I have a bunch of environmental sensors, and those make more sense to me to be displayed in hPa / kPa or mbar, but I also have my tire pressure monitoring sensors that would make more sense to me to be displayed in psi.
Look up customize.yaml, this will allow you to set most attributes for individual sensors.