Amethyst is the most features rich client app so that great!

One thing that I think that could be great to be integrated into nostr client are some kind of onchain bitcoin wallet where you could participate in a multisig setup coordinated on nostr. (Munstr)

Also multisig note posting like with Frost where nostr user can come together to maintain a multi-users organisation(npub).

But I think there is some missing NIP before it can be possible. So we will need to build some standard(nips) in order for that type of thing to be possible.