There are two Apple Pencils. The original is round, prone to battery death if you don’t charge it for a while, and is charged by sticking it out of a device’s Lightning port. The only current iPad for sale that supports it is the 9th-gen iPad. The second-gen Pencil (flat edge; magnetic charge/connectivity; all-round nicer) is supported by the iPad Air, iPad mini and iPad Pros, all of which are probably out of the range of most educational establishments. (There might still be older iPad mini models lurking in the channel, but I’m always wary about investing in old tech.)
I’ve no experience with the GAOMON. Wacoms are generally solid. My only advice regarding tablets would be caution. the GAOMON is not an independent tablet—it requires a compatible PC/Mac to drive it. I’ve no idea how responsive something at that price point would be either. Android + some kind of stylus would be an alternative, but you’re limited at the low end in terms of hardware quality and responsiveness — and at every level of Android regarding software. (There’s nothing to, say, match Procreate on Android.)