According to this post, it can be done. I managed to get them into SQLcl. But VSC-ext will not refresh. Instead I recreated one manually, that got stored in VSC-settings (at least with the password-obfuscation):

In a different post I learned, VSC-ext shall come with it's own inbuilt-SQLcl.
Questions:
- Can VSC-ext access the stored connections of the external SQLcl in %AppData%\DBTools\connections?
- How to start the inbuilt-SQLcl - my context-menue above looks way different from the screenshot.
Thanks