https://esphome.io < find a board + sensor pair here. Software stack tested with your board+sensor is hard to beat.
ESP32 boards: surprisingly fast/powerful little SOC with wifi
ESP8266: cheaper+slower. I like the Wemos D1 mini board: smaller and has enough horsepower for most things.
Sourcing: a ton on options on AliExpress. Buy a few extras so if you fry one you aren't waiting for replacements. They are super cheap ($3-$6).
Options to consider for board: memory, CPU speed (ESP32 vs ESP8266), size/form factor, pins/dev board or just solder holes, does it have built in USB controller (and which one), voltage regulator for 5V, USB Micro vs USB C, sensor voltage requirement, etc. Sounds complicated, but they are all pretty similar, and can typically buy a few and make your projects work. Getting one of the "branded" options like Wemos D1 is good bet, comes with all the basics covered, and no surprises like making your own voltage reg.
Sensors: lots to learn on each one. Just did the deep dive on CO2, and there were a ton of details (eCO2 vs CO2, auto calibration quality, manual calibration support, cost, airflow, etc). Went for Senseair S8. If you want easy place to get started, look at AirGradient Kit: https://www.airgradient.com/kits/
I'd recommend staying away from the 8266s at this point. The chip is EoL and the ESP32 offers double the speed, more than double the IO pins, and bluetooth. The 8266 is limiting with its single ADC pin, and single hardware serial and inability to define other pins for I2C/SPI.
I started with the 8266s thinking I wouldn't need the extra features, and most of my applications don't need it, but the few times I needed to work around the limitations weren't worth the aggravation to save $1-2.
ESP32 boards: surprisingly fast/powerful little SOC with wifi
ESP8266: cheaper+slower. I like the Wemos D1 mini board: smaller and has enough horsepower for most things.
Sourcing: a ton on options on AliExpress. Buy a few extras so if you fry one you aren't waiting for replacements. They are super cheap ($3-$6).
Options to consider for board: memory, CPU speed (ESP32 vs ESP8266), size/form factor, pins/dev board or just solder holes, does it have built in USB controller (and which one), voltage regulator for 5V, USB Micro vs USB C, sensor voltage requirement, etc. Sounds complicated, but they are all pretty similar, and can typically buy a few and make your projects work. Getting one of the "branded" options like Wemos D1 is good bet, comes with all the basics covered, and no surprises like making your own voltage reg.
Sensors: lots to learn on each one. Just did the deep dive on CO2, and there were a ton of details (eCO2 vs CO2, auto calibration quality, manual calibration support, cost, airflow, etc). Went for Senseair S8. If you want easy place to get started, look at AirGradient Kit: https://www.airgradient.com/kits/