I've been lurking across Lemmy and kbin from my Mastodon account. I tested the ability to post to Lemmy via a toot and it definitely works, but there are some drawbacks. I could only reply to comments that were within Mastodon's character limit. I could see longer comments if I navigated to the web page for the Lemmy post, but could only interact with whatever showed up in my Mastodon notifications.