It's great, isn't it? I was having a conversation with someone on here the other day and didn't realise they were on Mastodon. I'd shared the original post there and replies turned up in Lemmy and vice-versa. It's very cool.
The only thing I wish could be improved is the having to manually go back to your home instance and search for a community on another server. It feels even worse than the same process on Mastodon, which already feels clunky.
Ooh. I like this idea! When I'm at a computer again I'll look into adding a similar sidebar to !manchester@mcr.town