I made this case and diagrams for the PicoFlasher. Give it a whirl if you'd like. File for flashing the Pico Zero can also be found in this thread. You'll have to provide female pin headers, wires and get creative.
I'm also on the YouTubez.
My Ko-fi if you so desire to help feed some stray kitties.
Enjoy.
The author marked this model as their own original creation.