> Interesting GPU choice.. It's an Radeon RX550 Polaris-v4 card.

Yes, Lexa/GCN4. This choice has already been made in 2018 (see comment #140) and just upgraded from E9172 to E9174 and thus to 4 GiB VRAM from 2.

> I was not aware these actually work on PPC-BigEndian Linux.

Indeed. Let's wait for the prototypes with Linux to see how they cope with this.