PCP airguns require a way to fill to high pressure ~3000 psi. This is done with either a tank SCUBA or SCBA, or a hand pump. With the low velocity you will want for 10 meter
to 50 ft. target practice, one will get many shots before having to refill the rifle. A hand pump, then, is not all that bad---especially for someone young.
I'm going to suggest something like a Crosman Challenger, or the Airforce Edge. Though made for ten meter target shooting with aperture iron sights, these can easily be
scoped, and do not require any special scopes or mounts. The same model scope can be put on as he uses on his rimfire.
For the hand pump, I suggest the Hill, now branded by Air Venturi. Being that you are in a fairly humid climate (not like the high desert here), you will want the air drier, and
keep the drying media refreshed.
The chief advantage to a SCUBA or SCBA tank is that you don't have to worry about drying the air, unless you buy a compressor to fill the tank yourself. But, that is a whole
different level of commitment to airguns.
Single Stroke pneumatics like the Daisy 853, do work well, but the shooter must break position to charge the rifle for each shot. This is not as much of a problem for slow fire,
but for anything timed or relatively rapid fire, this can be tiring.
ETA: @ThePontificator This is not GD. You may want to edit your post above.