From their FAQ:

SWYP can replace any magnetic stripe based card. This includes credit cards, debit cards, loyalty cards, gift cards and frequent flyer cards, to name a few.

SWYP can store 25 cards encrypted in its memory. So there is plenty of room for all your cards. If you own a huge number of cards, no worries: the SWYP companion app on your phone can take care of the rest!

Your SWYP card ships with a card reader similar to the ones used at farmer’s markets and pop-up shops. Connect the reader to the audio jack in your phone, fire up the app, and start adding cards by swiping them through the reader. Your phone will securely and wirelessly transfer the cards to your SWYP card.

The thing that comes to my mind first: if this accepts gift cards, I wonder if I could load lots of VGCs into it. I'd then want to easily unload the VGCs after I use them (for example, when loading my BlueBird at Wally World). The video doesn't say how easy it is to delete cards stored on this thing.

Also, since it doesn't say "debit card" on it, and it doesn't have your name on it, I wonder if this would even fly for MSing. Cashiers sometimes look for my name on the card I'm using. At Wally, an occasional cashier even wants to see that the card I'm using says "debit" on it.

I'll probably stay old-fashioned for now.