Support for fragment links within collectives / smart picker

Is your feature request related to a problem? Please describe.
My collectives pages are structured with headings and subheadings. I want to create links from one collectives page to a section within another page.
Each heading has a # sign with a link to that heading itself but this is of limited use. If I copy that URL and use it within collectives, it becomes an external link. Preview is not working and anonymous users (who came through a shared link) cannot navigate but are prompted to login.

Describe the solution you'd like
I would like a way to specify anchors within a collectives page that work acroll all contexts, logged-in or anonymous. Perhaps it would be enough to extend the pattern for "what do internal links look like".
Ideally the smart picker offers a list of headings within a selected page, but that might be an enhancement for a separate ticket.

Describe alternatives you've considered
I have tried the smart picker to choose the referenced page and then edited that link to manually append the fragment part. This also breaks the preview for anonymous users. The link is no longer recognized within the shared context but opens a login form in a new tab.

Additional context
Nah, everything is said.

Start by inspecting the smart picker and the shared-link preview flow, then reproduce a heading fragment link in both logged-in and anonymous contexts. Done means an internal fragment link works across collectives pages and shared contexts without prompting anonymous users to log in; heading selection in the picker is described as a separate enhancement.