https://github.com/CodyTseng/nostr-relay-tray from nostr:npub1syjmjy0dp62dhccq3g97fr87tngvpvzey08llyt6ul58m2zqpzps9wf6wl I think they also have a hub to host those relays, if you don't have a webserver.

You can also use Citrine on your Android. Works with Amber and Amethyst. Can't be shared with others, tho.