See: Use channel search parameter with grid fields
The answer suggests that there is no way to search for grid field values. Is this still the case until now?
See: Use channel search parameter with grid fields
The answer suggests that there is no way to search for grid field values. Is this still the case until now?
That's correct. The easiest way to do it is with the excellent Low Search addon and use the Low Search Results tag as a drop in replacement for the {exp:channel:entries} tag and use the Field Search filter as described.
Remember to set the field and at least one of its columns as searchable. The values of the chosen column will be concatenated on a database column specially to be searched.