I mean, for a kind of museum piece, to get the true experience of using the computer I’d agree for sure just use original OS. But if one wanted to be able to use it for most functional purposes, it’s sad how the complete lack of backcompat in MacOS makes using an old MacOS tough — which is sad because new Linux often can work surprisingly fine on the same hardware. Like, current Debian on a 2008 Core 2 Duo is a fine computer that you can browse the Web and do basic office tasks on. It was shocking to me!

I want to run native containers without the orders of magnitude worse io performance than any other platform

As a Quad G5 owner, might I recommend OS X "Sorbet" It's an unofficial merging of OS X 10.5 with PowerPC builds of 10.6 components. Even on ancient G3's it out-performs both 10.4 and 10.5 in benchmarks

Wait... how'd you get it working on G3 machines? As far as I know, 10.4 was the last release for G3s.

Apple is pretty famous for dropping machines before they absolutely have to.

Yup get ready for the Mac Pro that was on sale at full price until a few weeks ago at $7000 to be removed from the compatibility list for whatever comes after Sonoma.

Lucky someone will make an installer that works for quite awhile until they change their processor again :)

Retro computing enthusiast "Action Retro" has demoed Sorbet Leopard on his G3 laptops [1]

[1] https://www.youtube.com/watch?v=h7Ponlb4QPY

His Pismo has a G4 upgrade card in it. So nope.

Yes but to be fair there haven't been a lot of ppc64 machines apart from Apple's G5 desktops.

And the same is true for Apple Silicon.

If you are basically the only one to use some piece of hardware (and you are the one who designed it) your software will be the most optimized out there almost by definition.

This is to say that the focus is on the decision to customize heavily your hardware. Once you decide that it's a pretty low bar to say that your software is the best there is for running on that hardware.