What you built is actually so great! Was also thinking of building something that makes blogging for less technical people easy without the downsides of a walled system.
Haven't heard of dev containers like that before, but cool to see that they can be used like that.
I do almost the same, but instead I use Astro.
I use Obsidian, with a GitHub submodule for the content, and host it all as a static page. I wrote about that here if anyone is interested: https://bryanhogan.com/blog/obsidian-astro-submodule