idk but a long while ago I was thinking of making a poetry and haiku one and couldn't see how to do it. LMK if you figure it out.
satellite.earth is the communities driven app. Not sure how the development is coming along, though, but it's a good browser based client. You can always use Spring with it on mobile.
But Spring + Satellite does not seem to support Amber.
From memory, Spring only stores your nsec in your phone, Spring is essentially a key-signer. Can't remember off top of my head who the dev is, perhaps nostr:nprofile1qqsph3c2q9yt8uckmgelu0yf7glruudvfluesqn7cuftjpwdynm2gygprfmhxue69uhhyetvv9ujuem9w3skccne9e3k7mf0wccsz8mhwden5te0dehhxarj94ex2mrp0yhxgetjv44hymmnwvhx6ef0qyghwumn8ghj7mn0wd68ytnhd9hx2tcwsryw4 knows more?