Interesting variant to the common outliner format used by Logseq, Athens Research, Roam Research, Dynalist, WorkFlowy, Tana, etc. I'm happy with Logseq for now but love to see new alternatives.
I'm not sure you can call it a new alternative. From my own usage I'd estimate that Treesheets is at least 9 years old. I used to use it for software project internal documentation, but have switched to Org-mode now. It's quite a impressive application.
I like logseq because it's one of the few editors to support org-mode (besides emacs).