I don’t have much skin in the game when it comes to GIFs or opinions on it. I don’t use them so I lack awareness. But legitimate question — is it an option to install a GIF keyboard app? That way you can use it on any iOS app, including Nostr iOS apps? 

 I had tried the giphy and tenor gif keyboards a while back but they didn’t work right. If I remember right, it inserted the wrong format of link and instead of embedding the gif in the note, the links would open in the external browser when tapped on.