If there's a case to make on Apple hindering a competitive landscape, then it would possibly be a case of violation of the European Union's DMA (Digital Markets Act), as Apple is not allowed to favor their own services over those of competitors in visibility, functionality, or integration within iOS. But the EU is a blunt instrument that needs to be sharpened sufficiently with explicit facts. And then still, possibly…
Apple has also shown its not shy about geofencing the remedies to only help people physically located in the EU's jurisdiction, with a billing address to match.
In a ideal world US would lead the way, as it's the most influential market especially for US companies. But I don't expect this to happen...