hey mike! with Android, you can use a piece of software that holds your key and manages permissions/access to it. this application on Android is called Amber. you can use it with apps like Amethyst, 0xchat, Voyage, Fountain, and then you can also use it as a 'NIP-46' Bunker, meaning applications that support bunker:// signin strings you can use those too. for example, you could use nostrnests.com with Amber to sign in so you don't have to use an extension or enter your nsec. you can install it from zap.store if you'd like to try it out.

If you are like me, you'll eventually want to play around with every new shiny thing that comes to nostr. Nostr relies on public/private keys. If your private key gets compromised, you risk losing your account. In theory, if you put your private key in bad app, that app could extract that private key from it. Event signers are an app thats separate from your client, that holds your private key and can confirm to your client that you want to so something (post, reply, like etc.). It sounds like a lot of extra steps for a minor concern, but I will say Amber has been mostly seamless for me. I do stuff on Amethyst and most of the time don't realize Amber is there doing the heavy lifting. You can set permissions in your event signer to require your approval to do things, or just do them automatically.