Simulate a Loop in Google Sheet Cell to Generate Alphanumeric String - google-sheets

Question

I need to generate a random alphanumeric string as a reference in Google Sheets. I couldn't find a loop function outside of creating a new function in App Script.
I used some existing functions and the new "Named Function" in Google Sheets to make something. It seems to work fine, but I wonder if there is a better way to do it.
The breakdown of what I did to solve this is:
Get a random letter between A and Z.
=RANDBETWEEN( CODE("A"), CODE("Z") )
Get a random number between 0 and 9.
=RANDBETWEEN( CODE("0"), CODE("9") )
Create a random binary value. (We added the +1 because the receiving function isn't zero-based.)
=ROUND( RAND()+1 )
Put it together in a CHOOSE function wrapped in a CHAR function to return a random number or letter.
=CHAR(
CHOOSE(
ROUND( RAND()+1 ),
RANDBETWEEN( CODE("0"), CODE("9") ),
RANDBETWEEN( CODE("A"), CODE("Z") )
)
)
That covers the mechanism to randomly generate a single character, but we need a string.
After some digging, I found that Google recently released the LAMBDA function, and combined with the MAP function, I thought maybe I solved it.
The MAP function takes an array, so I had to figure out how to create one dynamically, which landed me on the SEQUENCE function. Finally, I join the resulting array as a string.
=JOIN( "",
MAP(
SEQUENCE(1, 4),
LAMBDA(slot,
CHAR(
CHOOSE(
ROUND( RAND()+1 ),
RANDBETWEEN( CODE("0"),CODE("9") ),
RANDBETWEEN(CODE("A"),CODE("Z") )
)
)
)
)
)
Once I got this, I made a named function with an argument where I could pass in the number of characters or "slots" like this:
=RANDALPHANUM(4)
Below is a link to a demo sheet, would love to see how much better this can be.
https://docs.google.com/spreadsheets/d/1ODLkUm1maj5_5rxhr_KlmB3vI_OE_-fIyesAevlaogc

Answer 1

random weighted distribution between A-Z & 0-9:
=JOIN(, BYROW(1:4, LAMBDA(x, SORTN(CHAR({
RANDBETWEEN(48, 57); RANDBETWEEN(65, 90)}), 1,,
RANDARRAY(2, 1), 0))))
random non-weighted distribution between A-Z & 0-9:
=JOIN(, BYROW(1:4, LAMBDA(x, (SORTN(CHAR(
{ROW(48:57); ROW(65:90)}), 1,, RANDARRAY(36), )))))
if you wish to freeze it see: https://stackoverflow.com/a/66201717/5632629