Errrrr..............

Yes it is, its liquid CO2
NO! not allowed, CO2 is a hazchem, you cannot supply that under the description of "air" in the UK, and I would imagine the EU?...........totally illegal?

An "air duster", MUST contain compressed air, not carbon dioxide.............

Imagine you go to a garage and fill your tyres (tires) with CO2 rather than air?