Is there any way to make channel blocking in News actually work? I ask because it seems like every time I go to block a channel, it only gives me the option to UNblock it, i.e., I have blocked it in the past.
The sooner you stop using Apple News, the better off you'll be.
Visit the websites you're interested in with a browser like Safari instead with an ad blocker installed and using Private Mode (to minimize cookie tracking).
Search for the channel you want to block. Instead of tapping on the heart, tap on the channel to open it. A "dislike" heart will be available at the top-right of the channel.
Consider using "Feedly." You won't have to worry about blocking channels that don't interest you. You will also have more feeds and sources to view and read, versus Apple News.