How to calculate pitch fundamental frequency f( 0) ) in time domain?
This paper by Philip McLeod details finding pitch in the time domain, and specifically that it avoids the reduced resolution of equivalent frequency domain approaches due to the windowing required to eliminate spectral leakage.

https://cdn.instructables.com/ORIG/F3J/3Q7U/J20P2R5T/F3J3Q7UJ20P2R5T.pdf

I don't have experience with this approach but would be very interested in comparative results to the best frequency domain approach- if you could post them, assuming you pursue this further.