I just created Issue #6947: Control indentation of individual systems <https://gitlab.com/lilypond/lilypond/-/work_items/6947>.
If you are a regular user of \pseudoIndent or \pseudoIndents, please have a look at the issue on GitLab at the link above. I hope that the examples I posted on GitLab are helpful! If you have examples of other use cases to share, please do so. Gabriel
