I do like this a lot.
Since you sort of need to be there with the hat, it makes me wonder of you might get more response and/or geographic spread if you has some sort of leave behind. A sticker, or a card that you can slot in places.
I do think that leaving it as the gpg key is better, not a QR code. It helps ID this for nerds like you and me. I would never scan a wild QR.
Sorry if it seemed smug at all. The "My my" was more being happy that the Fdroid app repo is pulling it's weight and a valuable resource that fascists seem to over look.