Not yet publicly released, but it's been in beta for a bit, I've been testing it since March. There's a support forum here: https://multimarkdown.zendesk.com/hc/en-us/community/topics/...

It’s not out yet. It’s the Duke Nukem Forever or Half Life 3 of text editors. I’ve been waiting for it for years and years at this point.

At this point I’m not sure it’s relevant. Obsidian has eaten its lunch.