I mean, have you considered a dwarven wheelchair made from the shields of the fallen, using their frames for wheels that grant comparable protection while gaining grip compared with a wooden spoke?
Or a druidic wheelchair of entire roots that bonded to the druid when they were mortally wounded on the forest, bonding them permanently?
Or a warlock who walks with an artificial leg of miasma and lurching tentacles that his patron restored him to in exchange for his soul debt?
Literally no reason and no way a wheelchair in game is more a liability than some geriatric old fucking wozard breaking his hip or your characters having a concussion and needing an EMT.