Is there a way to hack YouTube landing page to see only certain topics?

it's intentional impossible by their design. they need to mix content because they only have so much advertisers for your profile on each topic, so you must move around as they don't get paid for many displays.

but you shouldn't be using their clients anyway.

One way that works moderately well is to mark certain topics as not interested when they are presented and like and watch the other topics for a longer time.

I've used the above to keep my YT landing page relatively clear of things I'm not interested in.

Once in a while it will suggest you a highly popular or interesting off topic item, but yea that is once in a while.

Basically what I'm saying is that we need to train their algorithm to our tastes through watching and marking things as not interested, don't show me this channel etc.

try it, maybe part of your problem will be solved

here is youtube with minimalistic interface https://invidious.projectsegfau.lt/

also http://piped.video/