Login via vanadium (grapheneOS) and nsec.app seems to be buggy atm. It worked once but after a logout the second login with nsec.app became a permanent "Loading..." message. Seems to work better with duckduckgo browser, but I had to refresh multiple times.
🚀🎉 Just rolled out ANOTHER update to https://npub.cash ! Yes, you heard it right - two updates in a single week! 🔥
Introducing:
🥜⚡️ Static Payment Pages - A landing page for your npub.cash address (https://npub.cash/pay/egge)%E2%80%A8
🎨🧙♂️ More design transformations powered by nostr:npub1r0rs5q2gk0e3dk3nlc7gnu378ec6cnlenqp8a3cjhyzu6f8k5sgs4sq9ac 
Discussion
Try opening nsec.app in a separate tab to see if starts working better. For nsec.app to work without a tab, it needs push notifications enabled in the browser, that seems to require google play services install and giving them some perms https://grapheneos.org/usage#sandboxed-google-play-installation
Please let me know if you try this and have some feedback. Thanks!