there is an app by the NIP author, check out https://www.youtube.com/shorts/gfItS5Qe6tI where Pablo demoes it. there is also a huge bounty to add it to Damus nostr:naddr1qq9rzd3cxycrxvpexvesyg86np9a0kajstc8u9h846rmy6320wdepdeydfz8w8cv7kh9sqv02gpsgqqqw4rswg3nxy but no takers yet. I'd love NIP-46 in Amethyst too.
Discussion
That is indeed amazing, and I looked at that keystore app before. The issue I see is that signer app has to be launched in the frontend to be able to listen to requests and sign anything, so it's probably gonna be not very convenient to use. And I'm not sure there can be a solution, at least on iOS. Anyone know better?