Sounds like a fun project, best of luck! Would love to see what you come up with. One word of warning with the misting: using them in an "upside down" configuration as I'm doing can be a bit finicky. I've encountered some that slowly drip due to the pressure of the water above them. Look for misting discs with small hole sizes (<=4uM) and expect that some percent of them won't work well. However, the ones that do drip at the start typically stop after a day or two of use and are fine from there on out.

I have not really considered decontamination and I don't think it's much of an issue for terrariums because the plants and soil in the enclosure already contain a lot of bacteria, etc. I could see it being much more important for your use case with mushrooms where a small number of mold spores can ruin an entire mushroom grow.