для нечетных дат:
=ARRAYFORMULA(FILTER(TO_DATE(ROW(INDIRECT("A"&A2):INDIRECT("B"&B2))),
ISODD(TO_DATE(ROW(INDIRECT("A"&A2):INDIRECT("B"&B2))))))
для четных дат:
=ARRAYFORMULA(FILTER(TO_DATE(ROW(INDIRECT("A"&A2):INDIRECT("B"&B2))),
ISEVEN(TO_DATE(ROW(INDIRECT("A"&A2):INDIRECT("B"&B2))))))