maegul , (edited ) 
Following #lemmy communities from #mastodon has gotten much better
Version 19.4 introduced automatic hashtag-ing (see https://lemmy.ml/post/16585416)
Posts get federated with a hashtag matching the community name.
The important bit is that comments to posts don't get the tags.
Which means you can follow the corresponding tag on mastodon and get a feed only of posts.
EG: #asklemmy
If you're starting a community, giving it a unique enough name could help prevent overlap too.
1/