@steveb53 You could get one of the little GL.iNet travel router boxes. These things allow you to connect to a WAN over a bunch of different ways: smart phone tethering, direct ethernet cable, 3G/4G USB modem, or even over a wifi connection.
I use one of these in a pinch, and it works great. There are newer models, with antennas and faster CPU processors, so plenty of options.
https://www.amazon.com/GL-iNet-GL-AR750-300Mbps-pre-Installed-Included/dp/B07712LKJM
In the manual, here's the specific section on the supported WAN connections. You're looking at using the "repeater" function to be able to get to the community wifi, like you say...
https://docs.gl-inet.com/en/3/setup/gl-ar750/internet/