Hi there,
Installing the pynq python package requires quite a few dependencies, including binary downloads. If you’re doing this on a Canonical provided Ubuntu image, your best bet would be to adapt some of the install steps from Kria-Pynq, I think that’s the closest we have to an example of installing it on non-PYNQ Ubuntu images.
Here’s a relevant post on this process An Attempt to Install PYNQ on Ubuntu for ZCU102
For creating a full PYNQ image, I don’t think you need to change much, you’re right you’d need to provide a zcu102.bsp and change the .spec file accordingly. There’s a relevant post on this as well: Failed to build PYNQ image file for ZCU102
Thanks
Shawn