Have you considered
CCI Quiet 22 ammo? It's a lot quieter than many of the pellet guns, especially those which push the pellet to supersonic speeds. And the Quiet 22 ammo has a lot more punch than the majority of pellet guns. And since you'd be using a .22 that you already have, you save the cost of buying a new gun. And you can always use your regular .22 ammo when needed.
I have snowbird neighbors and about a decade ago I popped a pest in the front yard with my .22LR and the neighbor lady's head swung around as though a stick of dynamite had gone off. She then gathered up her gardening stuff and went back into their house. Sheesh.
From that point on I stopped using regular .22LR (I guess the Velocitor was a bit much
) and started searching for something quieter. The usual CB ammo with 29gr bullets sucked. Not accurate and still pretty loud. Next, I tried the CCI Quiet 22 and it was very accurate with the 40gr bullets and nearly the same loudness as the CB ammo. I liked it a lot but then it became quite scarce during the big ammo shortage of several years back.
And that's when I ended up with my Gamo .177 caliber pellet gun. I really don't like it much although it does the pest control job. It's heavy and clunky and a single shot break barrel type. And with the lighter pellets it still has a supersonic CRACK sound that alerts the neighbors. BUT... I found some heavier pellets which don't break the sound barrier, so the only sound is a SPROIIINNG sound from the spring in the rifle when it fires. So quiet that it can't be heard at all from more than 15 yards away.
It's okay for quiet pest control. One thing I also learned is that regular rifle scopes don't like the shock of the recoil going forward instead of rearward. Air rifle scopes seem to hold center better.
