The Aranet has worked well for me, and I think is calibrated well and works smoothly. It’s not the cheapest though, but I haven’t recharged it in over a year… almost two years now!
We have one in office, I think more than 2 years already and haven't changed batteries. Bought new one, compared readings and CO2 readings were matching.
Was trying to look whether old one should be recalibrated (per instructions, have to leave outdoors for a while every <don't remember> months). However our office CO2 is already ~600-700ish when people are here, so maybe it is fresh enough for recalibration.
Ah, and home-assistant integration is finally available for Aranet https://www.home-assistant.io/integrations/aranet/