Great list, thanks!
I’d like to add another one: DistractionFree YouTube
It lets you manage the YouTube webiste by allowing you to turn on/off notifications, recommended videos and so on. Huge focus boost if you are able to look something up on YouTube without getting bombarded by clickbait videos about exploding wales and Illuminati conspiracies.
Also, an AdBlock goes without saying. For me, uBlock Origin works well and can quickly be customized on the go as you can turn it on/off for single websites with only one click.