I'm currently using Supply free Theme and have succesfully implemented tag filtering. I've modified the code a bit to allow the user to pick multiple tags from the same group.
I still have an issue regarding the filtering logic :
When I select two tag from the same group (let's say I want to see all the shoes that are color_white OR color_green, or I want to see all shoes size_9 OR size_9.5) I will only see products that have those two tags, instead of showing me all products that have one of these two tags.
I've search for all topics around tag filtering and haven't found any solution.