My table has data similar to the following:

update:

=INDEX({QUERY(SPLIT(FLATTEN(
 IF(Sheet1!B1:F=TRUE, Sheet1!B1:F1&"×"&Sheet1!A1:A,)), "×"),
 "where Col2 is not null order by Col1"); 
 TEXT(UNIQUE(FILTER(A2:A, A2:A<>"")), {"@", "@"})})