I use zigbee mqtt Which of course integrates with mosquito broker.

But I tied in my ecowitt weather station data via mqtt into the broker so I have it in HA. I did this with weewx . There's an mqtt add-on

I also integrated my blue-iris NVR in to mqtt for motion detection, notifications for cameras.

Life360 integration to help automate things based on who's home

I use esphome and have a bunch of sensors/devices. I track whole house power utilization, I have temp sensors on my HVAC to I can watch all its performance stats.

Here's my ugly drawing that tracks inside/outside/basement temps, geothermal water loop temps, in/out furnace air temps, water heater state along with both it and the furnace realtime watts usage.