Looking for audio recording advice

Some background here - I have a niche YouTube channel, mostly doing longform (often 3+ hour) commentaries on a board game with a friend. We're both very skilled at the game and are apparently entertaining to listen to, but it's all very amateur - I don't really know anything about videomaking except what I've picked up as I go.

That had never really been an issue, because the topic is so niche that only people really interested in the game watch, and they didn't really mind. But last year we got a shout-out from a big YouTuber and the subscriber count has gone up a lot since, to the point where it feels like I really should figure out how to make it a little less amateurish.

I want to start with audio, because that's 90% of what we do. But I don't even know where to start with it.

I got Blue Yetis for both of us a few years ago because I was vaguely aware that was a good mic, but if anything it made it slightly worse than just using headsets (quite a bit more echoey) - I don't know if that was a mistake, and if there are better mics to go for?

I'm also aware that you're supposed to have some kind of padding on the walls to stop the echoing, but that isn't really feasible for me both because I rent, and because all the rooms of the apartment I'm in are absolutely massive. I've heard that you can throw a blanket over your head, which I've tried for a short video but I absolutely couldn't handle for a three hour one. I'm lost on how to solve that too.

If anyone here knows much about it, I'd love either direct advice about it or a recommendation for how/where to learn about this stuff. It's super appreciated!