You can still track valuables and accounts that you can't sync or are not connected to a financial institution. This can be done by adding a Manual Account with a balance that can be updated by you.
With this method, you can track anything that is not able to be synced automatically.
To add a manual account, select the account type and add any relevant information
Additionally, if you are already tracking real estate through a manual account, you can convert that account to a Zillow account. Just change the "Sync value from Zillow" toggle to on.