That’s not a gun, that’s a hand grenade. There is no way that plastic is going to hold the pressures of a real centerfire pistol round.
The best they might manage is a one-shot device that destroys itself without harming the user.
It is only meant to fire a few times. I am pretty sure it will do that.
I believe the base model is in .22, but many centerfire cartridges have lower pressures.
They could use .32 S&W or .38 S&W. Both are still available.
Heck, they might be *more* available than .22 at the moment!