Several solutions have already been posted in here, please do not try to act authoritative when you don't know the answer. We already saw you asked what VNC is.
Yes I mean google wallet. I've never heard of a banking app supporting NFC payments by itself, I was not aware that was even a thing... googling suggests that might be an EU-only thing.
curious what people are asking and where you are when this happens? I would be shocked if I was just walking around my local grocery store and someone has any clue what Haiku is.
network namespaces can do it, firejail makes it easy but there's several other methods as well.
if you already know the IP address(es) you will be communicating with, it's even easier just by adding a static route with a gateway of the VPN interface.
I thought you needed root for app-level firewalls?