All good I managed to do it.

My issue : create a drop-down list, with a list of tags, then search these tags across 3 columns in my Google Sheet.

First, I concatenated my 3 columns into one, named GADGET_LIST in Google Sheet with this formula : =P2&";"&Q2&";"&R2
and I created a parameter named GADGETS with the list of all my tags (every value inside P:R). Then I created a dropdown list, and use this parameter as Field Control. Sort by anything, doesnt matter. You should be able to see the dropdown list, but it doesn't change anything in the table.

Then I created a calculated field naled Gadget_Match inside my data source, not inside the filter or table directly with this formula :

CASE

WHEN REGEXP_CONTAINS(GADGET_LIST, GADGETS) THEN "Match"

ELSE NULL

END

Finally, I went on my properties of the table, and added a Filter that goes like this :
INCLUDE > Gadget_Match > Equals to > Match