Experiences with infrared flush-mounted heating for bathroom wall/ceiling?

Hello dear forum!

With heat pump-typical low underfloor heating flow temperatures, an additional heater is often necessary in the bathroom to be able to reach 24°C or similar when needed. Common options are, as far as I know ...
- Installing underfloor heating under the shower and bathtub
- Running underfloor heating loops up the walls as well (supposedly quite expensive)
- Electric towel heaters
- Infrared mirrors
- Surface-mounted infrared wall or ceiling panels

Now I have come across very flat IR heaters for embedding into the wall or ceiling, e.g. Frenzelit Hicotherm mats or Carbon4 heating paint. Overall, such IR flush-mounted heaters seem to be rarely used in new builds for the above-mentioned case, the additional heating in the bathroom, at least I cannot find much information about them online and here it is hardly discussed either. What is the catch compared to the other additional bathroom heaters? I suspect that even for a small area it will be painfully more expensive than a mass-produced IR wall panel or mirror.

Does anyone of you have experience or recommendations regarding flush-mounted infrared heaters? Costs? Availability of installers?

Thanks to you!
Jo