Whitelisting Syncthing's network activity using firewall rules

I’m running Syncthing in a virtual machine (Debian guest under a Debian host) and would like to block this virtual machine at the host level from any other network activity, except what is necessary for syncthing’s functionality.

Is there a static list of internet addresses that I should whitelist (e.g for connecting to relays)? As for the local network, I intend to whitelist manually only the IPs of the synced devices.

Any advice on how to go about creating the necessary firewall rules?

There is no IP list for the global services but, for a special-purpose locked down device, you may not need to use them.