FILTER FUNCTION data with alternating rows dependent and independent values

I have data which I have tried to filter for all 4 rows but cannot do.

I have also tried to filter data in this layout and can succeed with filtering in paired rows but not all rows by using FILTER(......)+FILTER(......) which give VALUE! result

any help would be greatly appreciated: I may be using an inappropriate function but I like its simplicity compared to index match. But I will use whatever works. TIA.