3 weeks ago I posted a here and got positive feedback. So, thank you. I took it from demo to product spending on average 2 hours a day.
The backend is written in nodejs + postgres hosted on hetzner. I'm running it on the cheapest tier ~3Euro.
Most of the heavy lifting is done by postgres + graphile/worker [https://github.com/graphile/worker]. Images are cached on cloudflare and the server just sends ~400 btyes of json telling the browser what to fetch. I'm genuilly interested how much traffic I can handle with just 3 Euro.
The frontend is pretty dumb. Simple html (4kb) with a bit of alpinejs.