https://www.raptorcs.com/TALOSII
I just saw this, even if it is pretty old.
They continue the IMB powerPC architecture.
3mdeb develops coreboot for the architecture.
Here is an interesting presentation
OS Installation is complex, but Linux/BSD with support for ppc64 should work.
The used AMD Radeon Pro WX7100 GPU is pretty open, but the boot code contains blobs.
Just as the NVME controller.
This is a competitor to RISC-V, while the latter is in early steps but is high in trend and developing fast.
In the video the guy said that it is used a lot in high security contexts.
Imagine a scenario like in this talk where every device is scanned, the entire building is sealed, on springs, in a faraday cage.