Ok but the if you look at the Python standard library documentation, the basic documentation also doesn't list all magic methods separately for each type. See e.g.
https://docs.python.org/3.8/library/stdtypes.html#dict: it doesn't talk about __getitem__ but just uses d[key] and the documentation of special methods is a separate section at
https://docs.python.org/3/reference/datamodel.html. Maybe not a bad idea to follow that convention for MicroPython documentation projects - at least from a user's point of view, I assume most people looking for information on what a class can do would be interested in knowing d[key] works rather than whether that is implemented using __getitem__, which only comes into play for specific customisation purposes for instance.
Wrt typesheds, that's something else, but depends on what information the IDE needs I guess? E.g. when you use d[key] in an IDE, how is it going to figure out whether that works? By looking at the existence of __getitem__?