=LET(
firsts,MID("ㄱㄲㄴㄷㄸㄹㅁㅂㅃㅅㅆㅇㅈㅉㅊㅋㅌㅍㅎ",SEQUENCE(,19),1),
f_cho,LAMBDA(c,IF(AND(c>=44032,c<=55203),INDEX(firsts,INT((c-44032)/588)+1),UNICHAR(c))),
MAP(A1:A6, LAMBDA(txt, CONCAT(MAP(UNICODE(MID(txt,SEQUENCE(LEN(txt)),1)), f_cho)))))
CONCAT사용가능 버전용
=CONCAT(IFNA(VLOOKUP(MID(A1,ROW($A$1:$A$100),1),
MID("ㄱㄲㄴㄷㄸㄹㅁㅂㅃㅅㅆㅇㅈㅉㅊㅋㅌㅍㅎ",ROW($A$1:$A$19),1),1,1)," "))
2019로도 구현해 봤습니다.