I don't have experience with that yet. Are you talking about a PI hole? Can you give a little idea on how to make such firewall rules? Because I want to have a laptop with many VMs or Qubes and each VM has different firewall rules. An email qube would only allow connection to the email server. Maybe one of the safe browsing VMs would only allow connections to the websites I typically visit. The unsafe VM maybe to everything except for known bad IPs/domains.
And NSA and other potential adversaries most likely have access to at least one domain that isn't blocked by firewall.
You can buy for cents phone numbers online for one time verification purpose or even rent the number for long term if you need. It's better to use these anonymous cheap throwaway numbers if you want privacy instead of your real phone number for everything.