You'll only have to wait for a few minutes after they launch for evidence.
I remember the AirPods Max were supposedly overpriced garbage nobody would buy, and they quickly slipped to 2+ months waits for deliveries.
I think there's a lot of pent up demand for new iPads Pros. Especially since the last update wasn't very significant for most people. I'm confident Apple won't have a ton of excess stock sitting around in warehouses on launch day. 😂