Ah ha! It was Vexl. I’m still on their TestFlight, but I haven’t wanted to expose my phone contacts to a third party so I haven’t properly used it yet.

I’d love to see nostr:npub1mftv2j67vayavkks8rqev3u8jjhefe86tf80msstfxvpunk9vmps6prkl3 interoperable with Nostr so that I could use it with my nostr contacts rather than hoping to find a bitcoin seller in a big list of normies 🤣