I've definitely build portable systems in Django, back in the day. The trick was to have decent test coverage and run over both (at the time) MySQL and SQLite.

I've definitely build portable systems in Django, back in the day. The trick was to have decent test coverage and run over both (at the time) MySQL and SQLite. (And yes, I should have used postgres). I'll mention: The internet, in the nineties, was powered by 486-grade computers, and things were perfectly performant to a pretty decent scale. If you can get rid of issues like network latency (from e.g. a database on a different machine than your main computer), and similar 2020-era bottlenecks, a lot of web apps can serve millions of users from a single machine. That's doubly true with gigabytes of RAM and modern SSDs. With RAID and regular backups, it can even be pretty robust. It's even easier to do now that you can write static client apps that just need to push and pull little bits of data to and from the server. That's not an architecture that's used often, but it keeps things very simple and can work quite well.