Douglas, you've asked a very interesting question. Here is my own perspective on this -- speaking as a longtime Apple enthusiast who has shifted over to Linux
in recent years.
I think there can be good reasons for distributing MacBook Pro's with macOS on them. GarageBand, for example, can be a very fun first use of computers.
On the flip side, there can be very compelling reasons to install Linux on those MacBook Pro's. If the recipient students develop a familiarity with Linux, they will
be well positioned to use donated non-Apple laptops (or desktops) outfitted with Linux. Chances are high that future computer donations to your NGO might be non-Apple rather than Apple.
Also, Linux familiarity will give the students an advantage if and when they start exploring the Raspberry Pi and other homebrew electronics projects. For example, they might build their
Lastly, my hunch is that Apple will be discontinuing macOS sometime in the next few years. Mac computers makes up a smaller and smaller percentage of that company's overall income.
I can well recall when Apple discontinued the Apple II line of computers -- back in 1993. One day, they just said - "We're done making Apple II computers."
For that matter, Windows itself might have less than ten years left in its life. Microsoft is moving step by step in the direction of open source and Linux. So, in terms of giving students
general skills that will prepare them for many different scenarios in the future, Linux might make the most sense.
That said, if I were in your shoes I might send out half the Mac laptops with macOS on them -- and half with Linux on them. Students exposed to multiple operating systems may receive
the greatest benefit of all -- obtaining the kind of flexible thinking that will serve them well for whatever computers they might encounter in their future. Thankfully, LibreOffice works on all
major platforms -- so that can be a constant, familiar tool for students to master.
phil