You can log in with a bunker on jumble.social on your phone browser.

What you do is go to Amber, click the +, and click "add an nsecbunker". Give it a name like Jumble, and use the nsec.app relay or whichever one you want.

After you create it, you'll get a "bunker:// . . ." uri. Copy that, and while you're in Amber, make sure the app's notifications are enabled. If Amber can't send notifications, you can't use the bunker.

Open Jumble and go to log in. When you do, there's an option to "Log in with Bunker", you'll see a place you can paste the bunker uri. When you log in with it, you'll have to approve Jumble via a notification from Amber. Then it'll work pretty much the same as it does when it's signing for Amethyst, etc. and new kinds will send notifications for approval.