Repeaterbook does list GMRS repeaters.

You must have a valid GMRS or Amateur Radio callsign and be logged in to add a GMRS repeater. The system will perform a check against the Federal Communications Commission (FCC) database before allowing you to add the repeater to the database.

When the repeater is added, the call sign of the person who added the repeater is recorded and is allowed to edit the repeater. This means, if you hold both a GMRS license and an Amateur Radio license, you can add the repeater when logged in with your Amateur Radio license callsign. If the repeater holds your GMRS license and you added the repeater when logged in with your Amateur Radio license, you will be able to edit the repeater when logged in under either call sign.

You must have a valid GMRS callsign and be logged in with your GMRS callsign to edit a GMRS repeater. The callsign must be the same as the person who added the repeater or that of the repeater call sign.

If you have an account with your amateur radio license, you must complete a registration with your GMRS license and log in under that account. Repeaterbook requires registering with a unique email address. For accounts like gmail, you can try registering with the same email address you used to register your first account and before the '@' symbol, use the '+' symbol and add 'gmrs'. It would like similar to '[email protected]'.