To be brutally honest, the plane would crash about a second later, so approximately none whatsoever.
But this isn’t the right question to ask, as it isn’t the right question to ask why the wall was there. Why did the pilot and ATC decide it’s a good idea to attempt a gear up landing in the wrong direction is a good start.
I recall back in 2020, when Pakistan International flight 8303 belly landed at Karachi, slid down the runway, and then took off again and had a go at going around, the investigation showed that between them, the pilots just screwed up on having the landing gear down and had a go at landing without it for no other reason than they fumbled it.
The PIA pilots totally fucked up the approach, missed that they were very high late in the approach, dive bombed down to the runway at the last minute instead of going around. CRM issues -- the senior pilot plausibly couldn't actually fly (he had a history of bad approaches with unsafe descents) and the first officer failed to raise major problems or push back at all on unsafe decisions. When they first touched down gear up, they had dual stick inputs (one pilot was pushing down, one was pulling up) -- this is a huge no no. Communication in the cockpit was awful. Just lots of awful.
After the incident, PIA pilots were audited and determined like 1/3 had fake or suspicious pilot licenses(!!!). Lots of paying other people to pass tests for you. Internationally, PIA has been banned from landing by like all first world countries.
But this isn’t the right question to ask, as it isn’t the right question to ask why the wall was there. Why did the pilot and ATC decide it’s a good idea to attempt a gear up landing in the wrong direction is a good start.