WRT those phones, if they can connect to your own system at home you can run a tunnel - Wireguard, OpenVPN or anything similar - to it and escape to the outside

WRT those phones, if they can connect to your own system at home you can run a tunnel - Wireguard, OpenVPN or anything similar - to it and escape to the outside that way. This is more or less the same method as used to safely use public Wifi networks.