=DROP(REDUCE("",UNIQUE(K3:K11),LAMBDA(u,v,VSTACK(u,HSTACK("Week: "&v,SUM(BYCOL(UNIQUE(A1:H1,TRUE),LAMBDA(c,N(0<SUM(FILTER(FILTER(A3:H11,K3:K11=v), A1:H1=c)))))))))),1)
This would be my suggestion if i correctly understand what you want to do.