An Excel table has four columns, among which the 2^nd one is the grouping column:

We want to group rows of the table by the 2^nd column, from each group find rows where values in the 4^th column are "done", concatenate values of the 3^rd column of these rows, and form a new table using the new column, grouping column and row number.

Use SPL XLL to do this task:

=spl("=?.select(~4==$[done]).groups(~2;concat@c(~3)).(#|#1|#2)",A1:D7)

group()s function groups rows and handles each group; ~2 represents the 2^nd child member of the current member. $[] represents a string. # is ordinal number of the current member; #1 is the 1^st column of the table. concat@c concatenates members with the comma.

Source:https://stackoverflow.com/questions/78132082/returns-a-collection-of-values-for-each-row-with-two-or-more-conditions-into-one