If a .22, maybe a CZ in a chassis that you can adjust easily with growth. Easy to upgrade with barrels, triggers, etc. Centerfire? I would do the Origin, start with a .223 bolt head and same with the chassis. Down the road, barrel length, weight, caliber, triggers, even the chassis can be changed, modified, etc. All modular with a market for new and used.
I personally would go .22 as the venues for training, recoil, ammunition cost etc are easier on you and the young one. Down they road the loose interest, you are not out but so much and it's a gun you can shoot and keep around if the desire resurfaces.