I did something like this early on for a website builder using MySQL but it very quickly hit bottlenecks. I also wanted one-filesystem-per-customer support and

I did something like this early on for a website builder using MySQL but it very quickly hit bottlenecks. I also wanted one-filesystem-per-customer support and full isolation as in Docker, so I ended up writing a new OS to support all of this natively. It runs in production on boomla.com, a hosted website builder that is also a programmable platform. WARNING: it gets even weirder, databases can be nested, a database entry is also a file and a directory at the same time, or a nested database if you want. There is no way understood this sentence. :) For example, you can store files in files. As in, style.css/background.png, etc.. Every change also creates a new filesystem snapshot, which may also be nested. All right I stop here. This is not as much an advice for OP (to write a new OS) but more like a plug for the intellectually curious to explore a parallel universe. :)