Both my hobby and job have involved a mix of radio, electronics and computing. It started with radio and evolved into consumer electronics like stereo's and VCR's and then into industrial electronics and computers. Initially computers was hardware, then a bit of programming crept in. Hardware expanded to storage including san, and extended to datacentres and all it's equipment as well.

So in retirement I do a bit of everything that will keep me occupied, be it tinkering with an ESP32 or Pi project, extending my HomeAssistant monitoring or trying out new things like Modoboa or Grav.