Is the Pegasos made by Phase 5?
In Germany, 'Plan B' is a synonym for 'Shit, our first approach failed, now let's try our backup strategy'.
...Now guess why the company is called 'Bplan'
Everybody at Bplan was working for Phase5 when they were still around (Thomas Knaebel, Gerald Carda, Ralph Schmidt etc.). They even have old Phase5 machinery that is now located in DCE's building and is used to manufacture the Pegasos motherboards.
Wolf Dietrich is not involved. He vanished from the public as he would be sued for customer fraud immediately.
Is it the A-Box/PreBox with just a new name?
Not really. They're still trying to establish PPC motherboards on the market, and they're still trying to sell them to Amiga users (that's what MorphOS is about).
But the A-Box/PreBox/Amirage were custom designs. There were no off-the-shelf Northbridges available when these machines were designed, so Phase5 would have had to develop lots of custom chips just to make the system work. One of them (I think it was the A-Box) would have even had that 'Caipirinha' chip with 'stunning gfx performace'.
The Pegasos is (just like the AmigaOne) based on the POP reference design and built from standard chips which are readily available (VIA Southbridge, MAI Northbridge).