Closest to IG in what way? Specific IG functionality that you want to see?
Discussion
Strictly pictures / posting stories
So I'm using nostr:npub12vkcxr0luzwp8e673v29eqjhrr7p9vqq8asav85swaepclllj09sylpugg now, which feels a lot more like X/Twitter.
Out of the clients I've tried I think nostr:npub142gywvjkq0dv6nupggyn2euhx4nduwc7yz5f24ah9rpmunr2s39se3xrj0 is probably closer to an IG feel. There may be other ones, I haven't tried a heap of clients.