I think they go up to like 5000 feet so within anti aircraft gun range but you'd need a lot of such guns to cover the long Ukraine border and they are not cheap. Drones may be more practical.

>the Skyranger, a twin radar-guided 30mm gun turret made by Rheinmetall, making this the natural choice for the German Army. The gun system costs around $12 million https://www.forbes.com/sites/davidhambling/2025/09/10/why-so...

and ammo is about $600/round apparently.

EDIT:

They used to go 5000 ft or so. Now " fly between 2,000 to 5,000 meters to evade small arms fire, while the high-altitude reconnaissance drone Shahed 147 can reach 18,288 meters (60,000 feet). "

Eh, yeah, that's pretty far up to hit with small arms fire, at least until it begins to drop for terminal descent.