Here is what we ended up going with.
Bedroom:
600watt panel from https://www.infraroodverwarmingstore.nl
Controlled on/off and monitored by a Shelly Plug S - All Products - Products - Shelly
Configured as a Generic Thermostat - Home Assistant using another temperature (& motion) sensor I had in the room.
Bathroom:
Two 700(ish) watt panels (a mirror and a white ceiling panel) from Herschel Select XLS (less expensive) line: Herschel Select XLS - hoogwaardige infraroodpanelen
Controlled & wired to Herschel IQ Thermostat. Specifically this one, although any IQ Thermostat will do T-MKS Bedrade Thermostaat voor eenvoudige bediening van Herschel kachels
Connected via the Smart Life app, and pulled into Home Assistant via the Tuya Integration.
TODO: add Shelly 2 PM for energy monitoring
Hope this helps, links are to Dutch sites, but of course you choose what works and is available to you. Herschel makes some really high quality products, that are great as permanent installations, but starting cheaper with a Shelly Plug and an inexpensive panel is a good gateway drug in the IR world.
@teodoro.lio IR panels are an on/off type of heat, you power them, it takes a couple minutes to get up to 100 celsius (or whatever your panels are rated for) and then they start radiating heat to the room, once the room is warm you (or probably your thermostat) cuts the power to the unit. As far as I know there aren’t any panels available with a variable output.