If you use any Firefox browser, you can use Nos2x right now. But since Kiwi Browser is the only mobile browser that supports extensions, that's your only other alternative, assuming you're using Android. Kiwi is a really nice open source browser focused on privacy, and its support for chrome extensions is a stand-out feature. Something to consider. If you use iOS, j believe there's a Nos2x-like extension specifically for Apple devices.