So I have found an answer (but not perfect)
The formula =IFERROR(SUMPRODUCT($O$4:$AH$4;N(OFFSET($AH$3;0;-COLUMN(O3:AH3)+COLUMNS(A3:O3))));0)
Returns the correct values, but in reverse. As a result I then need to use=SORTBY(O28:AH28;COLUMN(O28:AH28);-1)
to reverse the formula.
Can someone help me pack all in one formula ?