I'm very late to join this thread, but since the Constant() node has now a kind field, we can possibly add this (though I'm not saying we should, depending on whether still this would be a nice addition to clinic docstrings.)

2 options that I can think off:
- Introduce a couple of new tokens (BIN_NUMBER, OCT_NUMBER, HEX_NUMBER). 
- Add a new field to the tok_state struct (like const char* number_type) and when constructing the Constant node in the _PyPegen_number_token, add that number_type as the kind field of the constant.

In case of anyone wondering, the latter would be a +20 lines addition (no changes on the grammar / tokens, just a couple of new lines into the tokenizer and the _PyPegen_number_token.)