Splitting on one or more spaces (\s+) gives us a JavaScript Array of sub-strings.
We can always get a consistently modified copy (map) of a JS Array by using its .map method, and specifying the modification in an item => modifiedItem pattern.
The modification here is that we take an existing hex string (let's call it 's'), obtain a copy prefixed with '0x' (signifiying Hex, in JS number strings), and apply the JS Number constructor to that prefixed string, to get a base-independent numeric value.
We now have a JS Array of base-independent Number values, which JS displays (or 'stringifies') by default in base 10, and when these whole Arrays get coerced to strings (the string passed back as a Keyboard Maestro variable), they become comma-delimited by default.
Thanks again for the explanation. Unfortunately, as already mentioned, this is far too high for my abilities. But of course there's always a lot to learn here.