The same as on desktop browsers.
There are so many ways developers could want it styled though. Using the few examples of existing native options doesn’t account for how many will end up using it. In fact, one prime use-case is to select an image itself, I haven’t seen one example ever of a select node being used to select an image without text being the primary piece of content in the node.
Once you introduce nesting an image in an option, you’re opening the gateway to having web-level layout constructs in it so developers can use it however they please. This is an extreme measure which would require revisiting an old component for a major overhaul
Though I believe the advantages mentioned earlier outweight this disadvantage.
I disagree with the “advantages” entirely (of which, I currently only see one case where it helps.) Modifying an element this old internally could lead to buggy behavior and/or existing sites breaking since they aren’t expecting the new functionality. We shouldn’t justify that kind of breakage without multiple clear cases where a UX is extremely convoluted and difficult to build without the changes.