correct me if i'm wrong but hardware-wise i don't see any link at all.
Not directly as there never where any hybrid Amiga computers, the transition started whit what happened after Commodore died.
There where many possible routes, one was DEC Alpha, another was going PowerPC, and there where many more ideas about what route to take.
In the end it was Phase5 who made the decision by creating the CyberStormPPC and BlizzardPPC, add-on CPU modules, and there plans for A/BOX, a next generation computer that never came to be.
While the CyberStormPPC and BlizzardPPC was running an other operating systems, PowerUP and WarpUP, it was start of a split in Amiga community about what was best Phase5 PowerUP, or Hagge&Partner WarpUP, latter WarpUP became part of AmigaOS3.5 and AmigaOS3.9 as bundled package.
Amiga Inc was not really interested in hardware, nor where they interested in the OS, all they wanted was recreate the glory of Amiga by creating an Game Engine, they called it AmigaDE, was based on Intent, (They tried rally hard to sell this idea to the community but not many liked it.).
But as people begged for a updated version of AmigaOS3.x, Hagge&Partner was contracted to do that work, Hagge&Partner had a long history whit Amiga and PowerPC, plans where made for a PowerPC based next generation Amiga, but after a while relationship between Hagge&Partner was broken.
So Hyperion entertainment did take over the development of AmigaOS, but this time the target hardware was PowerPC, they know they needed to support classic software so they created Petunia to translate legacy programs at run time. plus A wrapper for WarpOS was also created so that games like WipeOut2007, PayBack and Heratic II and other games where possible to run.
As some games that needed WarpOS where ported to AmigaOS4.0, the interest in WarpOS wrapper was lost, it was also tricky to get it working on all types of PowerPC CPU's like the AMCC4x0 chips.
But lets cut a long story short, and just say it was the Phase5 accelerator cards that is the hardware link to Classic Amiga computers.
Phase5 accelerator cards where used as development platform during early days of AmigaOS4.x development, even to this day you can run AmigaOS4.1 on a Phase5 PowerPC accelerator.