Cards and Gifts Sign

I really don't think it matters.

I don't think it matters but I personally would still write cards and gifts. Just in case.

I bought a card box that says cards on it and a gift sign, but I’ve decided not to put out my gift sign. My registry is online direct shipping to my apt and we’re traveling by plane so I’m not expecting physical gifts at the wedding either. I think people can figure out if they did bring a gift to just put it near the card box.

I think you're fine with just having a sign for cards, or an obvious "card box." However, I'd make sure there is space around where the cards will be left for physical gifts, if people bring them (so, it doesn't have to be labeled, but there should be space available). We have a relative who didn't register and "didn't want gifts," so she didn't think about having any place for them (or cards) to go. Guests brought cards and a few gifts. Since there was no other place to put stuff down, guests just started moving the place cards (which were displayed in alpha order) out of the way so they had someplace to put things.... It kind of made the place cards a mixed-up cluttered mess and there was jumbled pile of cards strewn across the table.... Make plans!

I did have a little sign that says gifts, cards, and wishes to the new Mr and Mrs

It wouldn't seem weird to your guests because this is standard wording!