Interesting project.
In a similar but opposite vein, I am going on a vacation and I wanted to share the stupidly expensive internet in my room at night with the family so I am likely bringing a raspberry pi to have as a travel router attached to my Mac. In this case, I can use the RaspAP project: https://raspap.com/
This is slightly different in that I do want a NAT.
I like this little thing: https://openwrt.org/toh/gl.inet/gl-usb150
You can use it as a repeater, so the whole family can just use the same network/password we use at home. And it is so small, you can run it from a power bank for hours.
Unfortunately, they are not sold anymore.
It's also slightly different because this project is for the Pi Pico.
Yeah, given the through put on the Pico is just 4Mbps in this setup, it will not work as a travel router for the family.