By the end of the 80s even the big non-MS players were largely irrelevant, and the entirety of the second half the 1980-2000 was MS. If you're talking about hobbyist/minor OS's, those are more available today than any time previously, depending on your definitions I'd argue hobbyist hardware is more available as well.
I'm not sure how Apple existing or not in the EU impacts that availability, but I haven't lived in the EU in almost 30 years and where I did live while there decided not to be there either, only for stupid reasons rather than visa limits :D
The demoscene and retrogaming scene in Europe proves how relevant those systems keep being even in 2024.
That's the later point I made: Apple existing does not, and did not, stop any of what you're saying you want from existing, and it didn't make it any less relevant either.
You're either talking about existence in the hobbyist/enthusiast sense, in which case apple's existence or not changes nothing, or you're talking about existence in the practical real world use sense in which basically no one other than MS was relevant for more than 50% of your stated time period, and even today apple's existence or not doesn't really change anything (if anything the existence of a large enough non-MS platform is what drove the cross platform frameworks like electron - for better or worse - that mean that a bunch of apps that would historically have been windows only are now also available on linux).
