which keyboard for my Ipad pro 1st generation (A1652) 12.9”

Your iPad Pro1 can be used the Apple Smart keyboard designed for this model, or with Bluetooth Keyboards - such as the Apple Magic Keyboard for Mac, or one of the many third-party keyboards.

Keyboards available directly from Apple:

https://www.apple.com/uk/shop/accessories/all/made-by-apple?page=1&f=ipadpro_12_9-keyboard&fh=47a7%2B4603%2B470e

The only keyboards available (from Apple online Store) for that model are these:

https://www.apple.com/shop/ipad/accessories/keyboards?page=1&f=ipadpro_12_9&fh=35d5%2B470e

Regards

Giulio

My pleasure