My first time seeing it too, it really does look appealing! I am using Scrivener's very generous Nano demo this year (https://www.literatureandlatte.com/nanowrimo). Free from Oct 15 - Dec 7, and at the end of that you get a 50% discount if you hit 50k words, which is pretty cool. So anyway, I've got my outline and stuff all in Scrivener but maybe I'll try iA next year, or for some other markdown writing work. It kind of reminds me of what Tomboy notes felt like in GNOME back in the day.
It was fun, and the setup is almost identical to iA Writer which I appreciate. I even had it all on my phone with Termux!
Last year I just did it in Markdown in VSCode in "zen mode" which also worked pretty well. It was definitely easier to setup than Vim and had better highlighting of bold/italics/etc.
