Hi Jonathan,
Sounds like a great device to have – your fermentation fridge will work great for incubation of mushroom bags too!
You don’t need much air exchange during incubation, so just opening the door a couple times day to flush out the CO2 which will build up from the growing bags, and replenishing the space with some fresh O2 will work fine.
Happy growing – let us know how it goes.
best wishes,
Adam