> As I already mentioned; IMO the idea is to follow the same logic than here:
>
> https://github.com/abo-abo/swiper/blob/471d644d6bdd7d5dc6ca4efb405e6a6389dff245/ivy.el#L427
>
> where `(thing-at-point 'region)` is basically the first branch in the
> cond.

`(thing-at-point 'region)` will work with the patch above.
Then we could add a customizable user option to specify
in what order the user wants to try things at point, e.g.

  `(region url file symbol)`

>>3. It would be nice to use (thing-at-point 'list) only when point
>>   is on the open/close parens.  This is how double-clicking by mouse
>>   selects the thing at point of mouse click.  When clicked on a paren,
>>   the whole list is selected by 'mouse-start-end'.
>>   'isearch-forward-thing-at-point' could be the same logic.
>
> now I use C-M-SPC for this selection and then M-w to copy and C-s
> C-y. If you add the command, then it will save the M-w and the C-y to
> copy the region, because region will be already active... But will
> require the M-s prefix any way... so not 2 but at least 1 bind will be
> saved. You can consider this option in the future if you want...

Yes, this is a nice way to yank the next list to the search with just
C-M-SPC M-.