>>>>>>>> +# C-M-f on '[' doesn't jump to after ']'
>>>>>>>> +hash['key']
>>>>>>>> +
>>>>>>
>>>>>> As discussed previously, there is no specific node which spans from [ to
>>>>>> ]. Some custom code could probably be written (there *are* leaf nodes for [
>>>>>> and ]), but the current capabilities of treesit-thing-settings don't offer
>>>>>> a good way to plug that in.
>>>>> Like for point inside strings, this might require more general changes
>>>>> that take into account syntax tables.
>>>>
>>>> Possibly, but I expect a solution that doesn't use the syntax table would
>>>> be tried first.
>>> Since there is no available information from treesit, handling
>>> treesit-forward-sexp inside strings/comments could forward to the syntax table
>>> like `prog-fill-reindent-defun' forwards to `fill-paragraph'.
>
> Shouldn't treesit-forward-sexp provide a way for ts-modes to override
> the default handling?  By default for all ts-modes such a hook could
> check if point is inside strings/comments then to use syntax navigation.

This is now implemented in bug#68993.  So here is the patch that 
handles such cases as C-M-f jumping from '[' to ']' in

  hash[:key]
  hash['key']

and from '{' to '}' in

  "abc #{ghi} def"