Would like a review/sense check of the components before ordering

Hardware
2

Here are some comments from looking at your list:

  1. The UART to USB is for if you are using the MH-Z19B carbon dioxide sensor. You can also just connect this sensor straight to the Pi.
  2. The Gravity pH and EC sensors with the ADS1115 have had extensive testing in Mycodo. See How to create a custom input with calibration using ADS1115 ADC and Gravity analog pH and EC sensors?
  3. There is a generic flow meter input that counts and converts the number of pulses from the meter to a volume, so the totalizer board isn’t necessary.