Drew Furgiuele came up with a PS script to import your SSMS Registered Servers into Azure Data Studio. He wrote it up in much more detail here:
Importing Registered Servers from SSMS into Azure Data Studio – Port 1433
If you’re just getting started with Azure Data Studio after being a long-time SSMS user, this might be useful. Do be aware that SQL passwords are copied over in plain-text. Drew notes that in the Github readme, but I wanted to call that out so people won’t miss it.
I’ve used this a couple of times in the past and it’s worked great to pull over my registered servers so I can start working in ADS right away and not have to go back and forth for server information.