I remember the same blog has a small feature on one of the obscure PowerPC-powered ThinkPads:
https://virtuallyfun.com/wordpress/2013/09/19/thinkpad-860-saga-part-1/
I remember a lot of noise about PReP and CHRP in the computer magazines at the time, but it seemed to fade away quickly. I have vague memories of reading this on Usenet, which makes it sound fantastic:
http://ps-2.kev009.com/powerpc-faq/
"The CHRP is an open platform agreed on by Apple, IBM, and Motorola. All CHRP systems will be able to run MacOS, OS/2-PPC, Windows NT, AIX, Solaris, Novell Netware, and possibly other operating systems. CHRP is a superset of PReP and the PowerMac platforms; thus you'll be able to run applications written for the PReP operating systems (OS/2-PPC, Windows NT, AIX) and the PowerMac (MacOS) on the new CHRP systems (under the same OS they're written for, of course)."
The FAQ also mentions a Mach-based version of UNIX for the Macintosh, which sounds promising. Imagine the interface of the Macintosh, but with UNIX underneath it! It's only $99:
https://www.tenon.com/products/machten/
It's as if half-way through the process Apple suddenly woke up, and realised that making an open PowerPC platform was fundamentally un-Apple. At which point IBM thought "sod it" and gave up.