I don’t care much for the interoperability between Mastodon and Lemmy, but having more users from Mastodon come to Lemmy sounds good to me.
Yeah, but if interoperability were better between Mastodon and Lemmy, you could just boost/“Retweet” Lemmy posts on Mastodon. Sadly, currently images attached to Lemmy posts are lost. Kbin is better in that regard than Lemmy (but has its own problems).