For the interested, I made another project whose frontend looks identical to this, but uses an sqlite backend synchronized with websockets [1].

It’s single-user, real-time and has authentication.

[1] https://github.com/nitrix/kanban

This is great. I think I saw it a few months ago too. I love how simple everything is, but still provides all the functionality I would need. The text and buttons are way too small, though, and I always have to squint at the expanding options because they're so small and low contrast.