I felt my diffuser's timer was too basic - needing to be manually turned on, then manually turned off by repeatedly pressing a button. So I connected an ESP8266 to the momentary switch, added some very simple ESPHome code, and now I have a diffuser that can operate for a few minutes at a time, or from any automation in Home Assistant that can be dreamed of.
I love that it's so easy to do this even to quite dumb devices. It turns something that was staying in a drawer and not being used into something that is now genuinely useful in providing a nicer space for my family.
EDIT: Sorry, seems the link didn't make it into the subject, so here's the full step by step https://digdilem.org/home-automation/smarter-diffuser/
Needs to be crossposted to nottheonion