The first solution is a hack and does not fix the problem with PDF Document Outline, if that is a concern:
= Heading
#set heading(numbering: (..) => none)
= Heading
This is basically the same exact issue I faced not that long ago, and the solution was to properly disable numbering for specific headings. This is also the only way to do this properly. But to select the headings…well, you have to write some sort of hack, like in How to conditionally disable heading numbering for some headings? - #4 by Andrew. If the if statement is indeed complex, then the per-level show-set rule won’t help either. Though maybe a combination can make the hack smaller.