Is the person doing the purchasing into 3d printing, or any friends/family into it? Might be worth inviting someone to spend an afternoon helping get the printer assembled. That's basically what happened with mine: I was hosting a craft gathering and a friend asked if he could assemble my Ender 3.

Tip unrelated to the initial set-up: assess what your son would be interested in printing and see if there's likely to be magnets or screws/nuts needed. A lot of models are designed with the metric system in mind and I've found that the local hardware stores have limited selections and extremely high prices for these things. Grabbing a metric screw set off Amazon may be a good idea to have a small stock of common sizes in a variety of lengths, but I've ordered most of my metric connectors off AliExpress and just have to plan ahead to accommodate the long ship times. In my limited experience, the M3 and M4 sizes are the most common (this would depend on the size of the item--smaller items may need M2s and larger items will likely take M5-M6s) and I find myself running out of the longer screws (16-20mm+). You may also want to look into thumbscrew versions of the metric screws. There's some printable models that will allow you to add a thumbscrew to a regular screw, but you lose a bit of the screwable length so you'll need to start with a longer screw.

And in the same vein: do you have hex wrenches? Your son may struggle using the wrenches that come with the printer, but maybe a more ergonomic wrench set can work for him.