9to5Mac has a thorough comparison of the new iPad Pro to its 2018 predecessor.

There are a few key under-the-hood improvements and additions, but the rest seems mostly like minor bumps.

Also, Apple’s site confirms the new (obscenely priced) Magic Keyboard supports the 2018 Pros.

https://9to5mac.com/2020/03/19/new-2020-ipad-pro-vs-2018-ipad-pro-comparison/

New 2020 iPad Pro vs 2018 iPad Pro comparison - 9to5Mac

This in-depth comparison covers the specs and details of the new 2020 iPad Pro vs the 2018 iPad Pro lineup for processor, RAM, cameras, price, and more.

9to5Mac
@chartier New Magic Keyboard cases are obscenely priced and will be late and likely hard to get (I waited over a month to receive the keyboard for my 2018), but I want one, dammit.