Random UUID in pure XSLT?

XSL Friends -

Today I write from the day job, where I am researching the question of how can
I go about producing random UUIDs, in dozens or hundreds, inside an XSLT
pipeline, without extension functions in Saxon. The Java randomUUID() function
works nicely when it's available, but I need to distribute the capability for
SaxonHE and eventually SaxonJS.

We do not have an available implementation of RFC 4122 v4 "random UUID" in
pure XSLT do we, free to use (and study)? I know the functional nature of the
language makes randomness, um, problematic (when isn't it?), which sometimes
means workarounds - that's all fine. Indeed so would calling out to a web
service if it is known to be reliable. I have thought about handing a list of
UUIDs in at runtime, but as I said, there may sometimes be hundreds and
perhaps thousands, which makes that approach seem a bit scary.

Any thoughts or perspective would be most welcome.

Thanks, Wendell