How to programmatically open a URL in the FE sidebar?

At the moment there is no such a function, but there is a plan (and it is already in one of the MRs) to create Drupal.frontend_editing object as set of helper functions. For example you can add this function https://git.drupalcode.org/project/frontend_editing/-/merge_requests/70/... as event listener of the click event on your link and it will be opened in the sidebar. Probably there should be a better way, I was just not thinking of such a use case. Maybe the editingClick function can be also split into more granular ones, so that the url can be passed as an argument and the sidebar is opened.

I am opened to ideas ;)