They seem an interesting project. They run their own Searx instance. Things like Easylist and Fanboys Annoyances can be easily enabled or toggled off.

It does not seem to be terribly different from other Webviews though. Privacy Browser, Fulguris, and Smart Cookie Web offer similar features.

It is still using Android System Webview unless you changed it with something like Graphene or DivestOS.

monocles browser uses Android’s built-in WebView to render websites. There are some limitations in the controls WebView exposes for managing privacy settings. For example, it isn’t possible to enable some JavaScript commands while disabling others. In the future, monocles browser will switch to a custom WebView called Privacy Webview https://www.stoutner.com/privacy-browser-android/core-privacy-principles/