UDF code to find last populated cell in a range of columns without using a loop technique

Hi. My first post, so here goes:
Looping backwards through as many as 500 empty Columns in a Row in order to find an occupied one works fine if you've nothing else to do; but it's too slow for my liking. In a VBA Sub I can jump straight to it with an xlLeft or I can use FIND(). I have thus far failed to discover a way to do this in a UDF. Similarly, I'm having to loop to locate colour marked cells along the same Row (using .Style). Can anyone point me in the right direction or am I simply asking too much of Excel?

Posting examples of code is a problem for me as my Mac can no longer cope with my Windows Office version after an update to Catalina. The Spreadsheet I am writing for is a laptop which I keep off the Internet completely.

Keep your masks up!

KGW

Thanks for your suggestion, bsalv. Not on a Mac, though. My Excel Application is on a PC laptop. I tried the range.end(xltoleft) method in Excel 2007 a couple of years ago and found it would not work when used in a function, although it worked perfectly in a normal Sub. The same applied to the FIND() Excel function - it caused problems in a UDF.
Have things changed since then, do you know?
Regards
KW

Thanks for your suggestion, John. The Index - Match - Choose complex is one I am not yet familiar with, so I found it difficult to parse your code. I take it to mean a one-dimensional array selecting the highest column number of all cells within the range A1:IF1 that are not empty. The code works when entered into a cell as an array, but how can I use it in a vba function? I also failed to find a way to copy the code down a range of 2100 cells in a column.
Any help would be much appreciated.
Regards
KW

Thanks again, bsalv, for your quick response.
Unfortunately, I cannot access your file as my Mac OS (on the machine that receives my email) requires Office 365, which I do not trust.
Regards
KW

Salut, bsalv.

Tried the xlToLeft solution. So far, so good; seems to be working in the test phase at least.
Nogmaals hartelijk dank.
Thanks also to John Topley, whose solution I shall study in more detail.

Regards
KW

OK, bsalv; I've got that covered. Thanks.
Regards
KW