So, if you want to follow a Lemmy community from your Mastodon account you can simply do so as you would follow any other account. It will treat both posts and comments on that community as boosts. This quickly clogs up the feed and is very confusing to navigate.
Is there a way to have it show only the posts in my feed?
Hm, yeah that’s a good point about them being boosts. But I guess it makes sense. If you view a Lemmy user from Mastodon, it mostly looks like you’d expect. So probably would require a coordinated development effort between Lemmy and Mastodon teams to agree on some kind of improvement.