I think posting to a group (like a lemmy community) is a good idea because they act like relays. On Mastodon, your posts are only sent to your followers and people you mention. If you’re not followed by anyone and don’t mention anyone, your post won’t be federated anywhere. Lemmy communities however will share your post with all their followers, allowing it to reach a larger audience. So unless you already have a huge audience, I think microblogging users that want to be heard can benefit greatly from interacting with groups.

To make microblog posts more appealing to Lemmy users, do consider separating out a plaintext line at the start to act as a title. Lemmy iirc takes the first paragraph of the body as the title if there’s no actual title given, and that can look awkward when that first paragraph is your entire post. This title shouldn’t include formatting or mentions or hashtags.