Snippet-ization in #51985 doesn't allow nesting

[DukePaulAtreid3s]

Is your feature request related to a problem? Please describe.

In my draft PR #76270, I am attempting to add a nested line to the SD card messages (snippets seen when the player uses the "examine photos" option in SD card apps), but its appears that whatever method #51985 used doesn't support nesting.

Solution you would like.

The ability for those functions to support nested snippets.

Describe alternatives you have considered.

No response

Additional context

I have no knowledge of C++ whatsoever, but I would very much appreciate any help in this endeavor.