If you don't have an extension on mobile you need to use nsec.app but it's better IMO to just use an extension for mobile.
nostr:npub18ams6ewn5aj2n3wt2qawzglx9mr4nzksxhvrdc4gzrecw7n5tvjqctp424 Can you explain to me how to sign into Nostr Nests without an extension? I'm trying to use moblie since my laptop is out of commission at the moment. #AskNostr 
Discussion
Brave doesn't support extensions. So you'd need to use Firefox or Kiwi on Android. Again if you don't want to use NSEC.app.
There are no releases on GitHub for nsec.app so I can't use Obtainium to install and update it.
It's a website. https://nsec.app
It's an nsecBunker that runs in your local web browser.
Couldn't seem to get nsec.app to work for me. Most likely user error.
Which browser/OS? At what stage did you have issues?
Android. Brave and Firefox.
Brave is problematic with nsec.app. Firefox should work, did the popup with nsec.app show up to you? Could you confirm the connection? If not then firefox blocked the popup 😟
OK. I think I got it working in the Mull web browser. Mull is a privacy focused branch of Firefox, which is available through F-Droid.
I used Firefox with extension. Pretty sure I got it working. Logged in. Not sure if I can be heard because no one there. Thanks for the help!
Brave has push API turned off by default, you'd have to adjust some settings to make nsec.app work properly