Comment by ClumsyPilot

The IoT hubs are an embedded system, built with a minimal memory footprint and overhead, 512 mb of ram is typical, sometimes less. Here is an example: https://www.gl-inet.com/products/gl-s1300/

That means you can't have docker and different versions of Java, node and .Net all running in parallel.

You run a single process and Sqlite is a library that allows SQL operations and database to be inbuilt. You 'budget' is like 100 mb of Ram, becauae other stuff has to run too.

All the time-series databases I know are a large, memory hungry hippo, built for distributed compute/kubernetes. Just very different usecase. If one was built with minimalism in mind, then it could be used.