Some say they are ok with normal saline, which is also often used to dispense other med, but I am not sure about 3% or 7% - much more inclined to clog and/or corrode.
If I was a bout to order a new mesh nebulizer, I would call the vendor, or better still the manufacturer, and find out. I might also ask if there is anything special I should do to keep salt crystals from building up. Boiling my Innospire Go every couple of days (not steaming - I don't know about that) kept it clear. If I tried to go a week, is started spitting and leaking.

I think there are a couple of mesh brands that say they work with saline but MOST do not.