I've never been able to watch The Office (UK version, I've never tried the US version since I didn't like the UK version), because I simply don't find cringe comedy funny.
There's definitely some cringe inducing moments in Joker.
His mother asking "Don't you have to be funny to be a comedian?" is downright painful. There's also the scene on the bus with him and the little girl, and him bombing at the comedy club.
The casual prejudice towards little people that we see from the clown company. Those are the big ones that immediately spring to mind.
The difference is that those moments aren't meant to be funny. I can deal with cringey stuff when it's treated seriously.
As to whether it's a fun watch? That's a tough one.
It's a dark tale, and it's definitely depressing. It's a couple hours of people being really crappy to one another.
At the same time though, I didn't find it actively painful to watch. I don't know that I could ever watch A Silent Voice again, even though I would recommend it as an excellent movie. That's a film that I wouldn't describe as a fun watch, and I think the Joker still is. There's a twisted vein of humor at the heart of the film, a sort of laughing at the cruelty of the world. That keeps it from being too dark, in my opinion.
UK Office was great, but I think you'd like the US Office; it's radically different and has a lot less cringe humor. If you skip the first season I think you'd enjoy the vast majority of it.
His mother asking "aren't comedians supposed to be funny" was absolutely hilarious. So was him dying on stage. it's dark humor, but it's humor.