Hacker News Reader

it's pretty prominent in a lot of browsers, like firefox and safari (from the top of my head)

Dunno about Safari, but at least for me the Firefox one lacked two features:

An official keyboard shortcut for going to reader mode.

The option of having the browser send all articles to reader mode when detected as possible.

Alt+V+R goes into Reader mode on my FF (without any extensions for that).

and ms edge