On twitter it highly depends on who you're following. If you specifically wanted to avoid political posts, it's not that hard to steer your algorithm that way. I follow ~130 people, and outside of maybe 4 of them who I like hearing political comments from, I only get interesting tech/tech-adjacent discussions. Almost zero politics.

In the past, whenever I get some politics stuff or celebrity news in the main feed, I just press "not interested" and relatively quickly those types of posts stop showing up.

On the other hand, I'm not sure who actually uses bluesky. Can't say I've ever felt the desire to go on there.