Dynamic Calendar in Excel 365

I tried part of the problem as a challenge; namely creating a blank calendar.  My approach starts with the idea that the 'natural' way for Excel to store references to an array is as a thunk.  I set out first to create a single month entry

CALENDARMONTHλ
= LAMBDA(SoM,
    LET(
        calendarMonth, 1+SEQUENCE(6,7,FLOOR.MATH(SoM, 7)),
        mm, MONTH(SoM),
        VSTACK(
            EXPAND(TEXT(SoM, {"mmm","yyyy"}),,7,""),
            {"Sun","Mon","Tue","Wed","Thu","Fri","Sat"},
            IF(MONTH(calendarMonth)=mm, calendarMonth, "")
        )
    )
);

Then the worksheet formula is

= LET(
    ym, DATE(yyyy, SEQUENCE(8,3,mm), 1),
    MAPλ(ym, CALENDARMONTHλ)
  )

That rather begs the question of MAPλ.

I had ideas to portion the entries out as monthly lists represented by an array of thunks, but didn't get around to that.