Speaking from experience, quite a few of the common Chinese tablet and phone models can be disassembled with practically no tools, and you can often detach the touch panel and screen entirely by hand or at most by desoldering the power cable (for the screen - not seen any soldering needed for the touch panel, as it's a common repair). Often the tablet batteries can be detached easily, as well though they're usually entirely internal, and the board can often be lifted out with no tools as well. They're really surprisingly serviceable.

Several of the boards of the devices I've had are exactly the same layout across multiple brands and with easily identifiable connection points for additional connectors etc.

The main limiting factor for doing this is that the touch panel is often the first to go (scratches, getting chipped or smashed totally - I've ruined 3 touch panels so far...), and many of the devices are so cheap they're not worth the hassle to repair vs. upgrading to a newer, better model cheaply.

E.g. my five month old Chinese phone has 1280x720 screen resolution. Similarly priced phones now tend to be a bit larger (5" vs. 4.7") and come with 1920x1080 screens. I cracked my touch panel recently (by sending the phone flying halfway across the room so I really can't fault the phone - other than a few cracks it's still working fine) and opted to order a new one for ca $40 this time, but had the screen gone too I probably would've shelled out a bit extra and just replaced the phone instead.