Project Idea: travel vpn router using a raspberry pi 4

Hey guys, in short, I'm trying to make a travel VPN router using a raspberry pi 4 it's a simple idea connect to public wifi and then tether it back with VPN, I decided to install open WRT for that, but I faced a problem how do I make a custom interface to make it more user friendly to change wifi networks or change VPN configurations, etc, any tips on how to make a custom interface I'm totally lost.

check travelmate package.