Yes, you are correct that the 1099-G for CA does not have box 10. Box 10 is for state withholding. Since this is a 1099-G for state refund, you do not need to be concerned with Box 10. The state refund would be reported in Box 2.
Typically, state refund is not reported as income on your 2021 return unless you itemized in 2020. If you took the standard deduction in 2020, then you do not have to report the 1099-G for a state refund.
If you did itemize in 2020, you need to enter the 1099-G as income in the Wage and Income section of TurboTax.
Just leave all the boxes blank in TurboTax except for the boxes that are amounts entered on the 1099-G.
