How does it compare to NextDNS?

If you have used YouTube ReVanced on Android, I think you can figure out how to use https://github.com/Balackburn/YTLitePlus using SideStore

You can use NextDNS to block ads at DNS level

What if I want to browse the Firefox subreddit in one place, where all its content is gathered in a single location?

It doesn’t help that Firefox will still be at different places with different contents. They should do something about user experience. It’s very confusing for non tech savvy people.