For anyone who signed up when me.dm was in pilot mode - and have been getting "account not yet approved, you will receive an email when it is" or something like that - just sign up again.
That was me, I was already on Mastodon, wanted to see what Tony & team would turn that particular instance into (e.g. any direct visibility between Medium articles / comments and Mastodon).
Personally I tend to write comments too long to fit into 256 chars (e.g. this one) so I was hoping for some kind of hybridization. ActivityPub 2 can pass much larger blocks of text around, so that's a possibility.
As it is, I haven't yet decided to migrate my previous Mastodon account from mas.to to me.dm - mostly because I rather like the local 'timeline' there.
Just my $0.02...