Apple is not here, just fellow users supporting these communities. Pages does not support your inventive list style unless you are prepared to enter and format it manually. The only means for the Pages product team to see your
request is to submit a feature request via the Pages application menu item Provide Pages Feedback.
Let the Pages product team decide how easy adding and supporting code changes to Pages might be. After all, it took them 8 years to add back non-contiguous text selection.
Microsoft Word v16.89.1 (Office 2021 for Mac) allows one to choose the initial paragraph symbol instead of a number, but as far as I can tell, does not allow one to combine that § character with a subsequent number in a new list definition. If Microsoft does not allow this after 38 years of Word development, don't count on the Pages product team being bellwethers.