The recent filter=tracked feature is somewhat related to this.
https://github.com/discourse/discourse/commit/88dcdf776bf1ea0f4cc9a4245a123ffdc2a4abb0
However, the commit message explains that in this filter we:
do not include explicitly tracked and watched topics outside of
the tracked categories and tags.We can consider a
filter=all_tracked
to cover this edge case.
So filter=all_tracked is what would satisfy the use case discussed here.