There are plenty of other VPN clients in the store already that utilize strict confinement, there are firewall tools and surely enough others that use and open http/s ports, you should really try strict first… there is also no supported category at Process for reviewing classic confinement snaps that would fit your use case which is a hard requirement for getting classic granted.
Some combination of network-bind, network-control, perhaps firewall-control and network-manager (if you integrate with that) should suffice to gain enough access to kernel and the OS network features for your app