Schedule View By Event

BryanD55 One possible dynamic array solution for MS365 could be:

=LET(
    input, A3:I10,
    dates, DROP(TAKE(input, 1),, 1),
    times, DROP(CHOOSEROWS(input, 2),, 1),
    events, DROP(input, 2, 1),
    test, events <> "",
    names, TOCOL(IFS(test, TAKE(DROP(input, 2),, 1)), 2),
    keyId, TOCOL(IFS(test, events & "|" & dates + times), 2),
    ids, SORT(UNIQUE(keyId)),
    recordCount, MAP(ids, LAMBDA(id, SUM(--(id = keyId)))),
    maxCount, MAX(recordCount),
    newRows, maxCount - recordCount,
    cols, SEQUENCE(, maxCount),
    pad_ids, TOCOL(IFS(newRows >= cols, ids), 2),
    resize, WRAPROWS(SORTBY(EXPAND(names, ROWS(keyId) + ROWS(pad_ids),, ""), VSTACK(keyId, pad_ids)), maxCount),
    output, HSTACK(TEXTBEFORE(ids, "|"), INT(TEXTAFTER(ids, "|")), MOD(TEXTAFTER(ids, "|"), 1), resize),
    headers, HSTACK("Event", "Date", "Time", "Participant " & cols),
    VSTACK(headers, output)
)

Adjust the input range as needed. See attached...