Looks like "tree style tabs" extension on Firefox.
Alternatively you can try Floorp browser (fork of firefox) which includes this by default. It's like a mixture of Vivaldi and Firefox, but mostly Firefox.
You do have a point, but each App's play store page itself shows whether it has ads or in-app purchases. One can use that as an indicator for selecting an app. So people just need to pay attention to the small text right below the App's title
Then there is always f-droid . You can find really good quality software without ads in fdroid. I rarely use the play store these days (except when I have to update whatsapp and banking apps)
I think there are services which offer temporary phone numbers like mysudo for instance. That being said, I have never used such services so I don't know how viable it is.
I have been putting this off for some time now as the RSS feed in qbittorrent was sufficient enough for me. (Also storage space is quite limited on my computer)
Hey thanks. It still doesn't have that google material U ish aesthetic that I'm looking for but that's okay.
I also found another theme named - Bazik