I have come to really like My Google Thermostat.
I fitted it during first lockdown. Primarily, because I was bored. I had spent a couple of days draining the system and doing general maintenance and thought, why not?
We had a perfectly good programmer, but I fancied a change.
It was an easy fix because the room stat was next to the programmer in the hallway, so no extra wiring to do.
Would not be without it now.
Simple things like being able to crank the heating up for our return if we have been away for a few days, or boosting the hot water at a specific time or need.
Not sure my wife agrees though. She is working from home, and every time she's put the heating on this week, I have turned it back off