Basically a laptop without a battery and keyboard, generally not much you can do to one but replace memory and storage and that seems to be all ASUS lists as potential options (aside from the various CPUs soldered to the board)
Basically stuck with integrated graphics. Now it does have an M.2 slot, so conceivably with a lot of investment you could get an M.2 to PCIe x16 adapter, an external power supply, and a GPU. A lot of that depends on which CPU you have, if it is one of the lower end ones, probably not worth it.
It also has room for a SATA SSD or hard drive, so you would have to have one of those for the OS in place of the M.2.
So power supply, janky adapter, possibly a switch to SATA storage (you would pretty much lose the M.2 drive, so maybe a USB enclosure to turn that into external storage), and a GPU.
Better off finding a used desktop for that kind of money and putting a low end GPU into it.