Excel function to construct an array from values without VBA

NB This question refers to some features like optional LAMBDA arguments and the ISOMITTED function which are only available (at the time of writing) in the Beta channel (more info here)

I am trying to mimic VBA's paramarray in an Excel LAMBDA function, so would like a function:

=ARRAY(arg_1, [arg_2], [arg_3], ...)

...which returns the array {arg_1, arg_2, arg_3, ...} dynamically sized according to however many args were passed.

If I know the number of args, I can just use the choose function like this:

=CHOOSE(SEQUENCE(number_of_args), arg_1, arg_2, arg_3, ...))

But I don't want to pass the number of arguments as a parameter, I want that to be dynamic. One idea was to do a binary search with ISOMITTED(arg_n) to find the first missing argument. But that still hardcodes an upper limit on number of args to my ARRAY function, not to mention creating a nasty binary tree hardcoded.

This is of course easy with vba:

Public Function ARRAYFROMARGS(ParamArray args()) As Variant
    ARRAYFROMARGS = args
End Function

Although this can only accept values which can be coerced into Variants so not lambdas or linked data types for example. This makes the non-VBA version more flexible.

Well as I alluded to in the question, I've found a way to use a binary search to evaluate how many arguments are missing. It does involve a lot of copy-paste though. So here's code to evaluate the number of args passed by finding the first which is missing:

_{Easier to copy versions here}

It is called like this =ARGSCOUNT(arg_1, arg_2, ..., arg_63) from an enclosing LAMBDA. Note it takes up to 63 optional arguments because my binary tree is symmetrical so must be a power of 2 (minus 1 for the case of 0 arguments) and named references have a low character limit around 2000. However you can call it more than once from a parent function and sum the result e.g. ARGSCOUNT(arg_1, ..., arg_63) + ARGSCOUNT(arg_64, ..., arg_126)

Then that count can be used in a second LAMBDA function to build the array:

Nasty I know, but that gives you access to a surprisingly simple function:

=ARRAY(A1, A2, 3, "foo", "bar") // array of anything, dynamically sized

BONUS:

You can even create an array of LAMBDAS to pass to something like map:

=MAP(ARRAY(LAMBDA(x, x^2), LAMBDA(y, y+1)),LAMBDA(f, f(3)) // -> {9,4} i.e. 3^2, 3+1

... and the vba ARRAYFROMARGS func can't take LAMBDAS as arguments.