Is there a way to create a “live” table of contents? As an example, if I use H1 as a page header, then it updates onto the TOC page?
Not an auto-generating, auto-updating TOC.
A #heading inside a file wouldn’t be recognised by Scrivener as a TOC item as its TOC output is based on binder structure (document breaks) rather than internal document headings. And a #heading as a file name is just another binder item. It is possible to create a link to a specific line inside a file, but not in a way that generates a live TOC.
While the binder acts as a de facto TOC, a manual TOC at the top of a manuscript can be useful: start with a blank file and just drag and drop folder and/or text titles from the binder into the file. In split view, this can be useful as a way of navigating between a restricted list of items, saving the need to trawl through the entire binder. It can also be used during compile as a TOC, if desired.
Users can, of course, use copy-and-paste options to create a manual TOC of all binder items or of some of them, but this doesn’t automatically update when a structural change is made to the binder. Close, but no trumpeting fanfaronade.