I use Brave as my go-to "website doesn't work in Firefox so I've got to use Chromium" browser on my phone. The constant cryptocurrency ads are really putting me off. No matter how many times I go through the settings, there's always some kind of cryptocurrency feature being placed front and center.
I guess they must be making their money off crypto bros in some fashion, but this crap is preventing me from doing anything more than necessary in that browser.
I don't think it's worth it to build Firefox from source when there are so many tiny projects out there maintaining slightly altered versions of Firefox already. You can do it yourself, but then you need to go through every line of code to check if they've added something suspicious and probably end up with some old, vulnerable version as your main browser (because who has time for that stuff).