Webtunnel 10.0.0.2:443 FINGERPRINT url=https://yourdomain/path

Support Relay Operator
1

What does the IP in the bridge-line refer to?

webtunnel 10.0.0.2:443 FINGERPRINT url=https://yourdomain/path

Last line Tor Project | Compile and run WebTunnel from the source

2

The IP isn’t actually used in the case of some transports, including WebTunnel and Snowflake. However PluggableTransport mandate one is provided.
You can put any IP here and it should work the same.