Your mention of composing dataflows reminded of this project https://nodered.org/ https://nodered.org/ which I haven't tried myself but sounds a bit like what Y

Your mention of composing dataflows reminded of this project https://nodered.org/ https://nodered.org/ which I haven't tried myself but sounds a bit like what Yahoo Pipes was back in the day. I'm also curious about how simple we can make self-hosting on bare metal hardware. These days I've been looking a bit into Gnu Guix where you can define a whole server system using lisp syntax. My current explorative sideproject is to try and setup a Gitea service with Guix on a Raspberry PI.