The only issue that makes this interoperation unusable really is that Mastodon groups representing Lemmy communities just “retoot” every single comment, obliterating the TL of anyone who dares to follow those groups. Which as far as I know only happens because Mastodon refuses to be cooperative and properly follow the standards.
Pleroma/Akkoma deal better with this, The groups there only retoot the main topic, and the answers you only see If you open the main topic, then you see all the threads.
Blaze