How can I add the colon to a list of MAC addresses in an excel sheet that has several MACs in one cell?

I have an excel with several MAC addresses and I need to add the colon to them. All cells have multiple MACs. For ex. XXXXXXXXXXXX, XXXXXXXXXXXX, XXXXXXXXXXXX. They are split by commas.

Is there a way to do it without splitting the MACs into its own cells?

Maybe you could try something like this:

=LET(
     a, TEXTSPLIT(E2,", "),
     b, MAP(a, LAMBDA(b, TEXTJOIN(":",,MID(b,SEQUENCE(6)*2-1,2)))),
     ARRAYTOTEXT(b))

• Split the strings using TEXTSPLIT() where the delimiter is a comma,

• Use MAP() function to execute a custom LAMBDA() function to split by every 2 characters and then join again by a colon,

• Finally, using ARRAYTOTEXT() to concatenate the strings into one.