YouTube has RSS for channels: https://support.google.com/youtube/answer/6224202?hl=en

RSS for Twitter sounds good. I don't have a Twitter account and used to follow a bunch of accounts via RSS but they shut that down a while ago. PHP is a turn-off though.

Does anyone know a tool, which would "convert" changes on the webpage into RSS stream?

I get, that is exactly what RSS-Bridge does, but it supports limited number of bridges. I'm looking for a way to track for HTML changes on ANY page.

Prevously, I used page2rss for that, but it shutdown few years ago.