I wonder if this would get moldy.
The condensate (water vapor that gets condensed out of the air in the process of generating the electricity) has to go somewhere; if it's not properly handled, yes, I would expect mold.
Some heat pumps have built-in UV-C sanitization to prevent mold.
You can install an aftermarket UVC light to sanitize to prevent mold in heat pumps, humidifiers, etc
Mold isn't really your main concern tbh. Instead it would be Legionnaires' Disease.
https://en.wikipedia.org/wiki/Legionnaires%27_disease