Chartbrew offers some different options for integrations such as custom API integrations (works with any REST API), MongoDB, and Firebase.
Also Chartbrew is not as complex as PowerBI which can be both a minus and a plus, depending on the use-case.
The pricing is a bit strange since you apparently pay by the hour you show users the dashboards and monthly, it starts from $700+/m which is much more than Chartbrew as a service (which is also free to self-host).
Another thing I'm not sure PowerBI has, are templates so that you can replicate dashboards for separate clients. In Chartbrew you can create your own custom templates or use the ones already created in the platform.
But before starting to use any of the services, make sure you data sources are supported by the platform.