Excel's formula version of Black cat's VBA:
Formula in B2
: =A2
Formula in B3
:
=IFERROR(SCAN(B2, A3:A10, LAMBDA(current_time, dummy, XLOOKUP(current_time + 30 / 60 / 24, A3:A10, A3:A10, "", 1, 1))), "")
Basically, it is trying to use a dummy array in SCAN
to get away with a recursive lambda.