Does anyone know what the legality of these are? Can you get in trouble just for purchasing things like flipper zero? Or just for using them in some way?
Transmissions are pretty tightly regulated in most countries. Receiving less so but those laws can be pretty catch-all. Unless you enjoy static noise you're probably intercepting something and thus potentially running afoul of lawful interception rules.
Exactly laws & whether anyone cares are ofc dependent on your country