I have had players make persuasion checks against me before when they want to do something that's explicitly outside the rules but I think it would be cool. Depending on how cool I think it would be, the DC can be anywhere from 10 to 20, and the player doesn't have proficiency
Taking away someone's intentional, roleplayed disability definitely falls under "infringing on someone's fun", though. If the player (not just the character) is also disabled and trying to represent themselves in the game, this goes beyond infringing on fun straight into lowkey offensive. I would never let this nat 20 work. Maybe it fixes the wheelchair or something.
Main issue is the wheelchair itself. No adventurer would ever use a wheelchair, the only reason we can use wheelchairs now are uniform roads and ada mandated ramps. Magic carpets exist and are cheap in game and don’t make you a liability.
Why do people think this? Like, I'm not mad at you, just amazed at how common this belief is.
Wheelchairs were around, and in use on surfaces that were abysmal in comparison to modern ones, but they worked.
Whether or not an adventurer would use one is a different issue, but folks really don't know shit about wheelchairs it seems.
I'm not saying it would be fun, or easy, but I've been out in the woods on paths barely wide enough to fit a chair, and had people, my patients, push themselves the entire way, lumps, ruts, rocks, roots and all. And rubber tires aren't magic for that. They help, but they don't make the impossible possible, just the edge cases easier.
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.
D&D is ultimately a set of rules to guide a group improv storytelling session. One of the first rules of improv is "yes and" so you go with it within the confines of the game rules as well as what people are comfortable with. This is where /u/starbuck@lemmy.world's suggestion of "Ranlar slowly rises from his wheelchair before collapsing under his own weight as his atrophied legs give out. Your party must now find a way to move him away from the orcs without using his newly healed legs, perhaps on a nearby chair with wheels." Fits so well. It "yes and"s the spell while remaining true to the other player's wishes.
The DMs job is to maintain the fun for the players, and if one player is ruining others fun they need to be spoken with and kicked out if they aren't able to be a team player. Personally, I treat a NAT20 (and critical failures) as an opportunity to do something comical that helps advance the story and improve the lore, because that creates the moments you tell to others when sharing fun stories about D&D