Hi AndriiO1895 - the private endpoint from the watcher to ADX lets the watcher connect to ADX and ingest data. But to access dashboards, your browser needs to connect to ADX. If that connection uses public connectivity, disabling public access to the ADX cluster will block it.
There are various network configurations that can let you connect to ADX from the machine where the browser is running using private connectivity. For example, if you have VPN or ExpressRoute connecting your machine to an Azure vnet, you can create a second private endpoint in that vnet for the same ADX cluster. Additional DNS configuration might be necessary as well, you might need to check details with your network team or open a support case with the Azure network team.
Thanks for the question, we will clarify this in documentation.
We are working on adding the ability to add multiple databases as targets in one operation. In the meantime, a workaround is to use Bicep or an ARM template, where you can define multiple targets in a single parameter file.