A new post titled "Current status of coreboot and Heads ports for Talos II" has been published on the coreboot blog. Find the full post at https://blog.3mdeb.com/2022/2022-02-16-talos2_coreboot_status/

This post summarizes our current progress on making first coreboot port for POWER platform*, including Heads as a payload. It will also show how You can test it without having to actually flash firmware to PNOR permanently.
Description of OpenPOWER boot process and coreboot’s place in it can be found in previous post under OpenPOWER tag.
*) there is already a target for qemu-power8 that compiles successfully, but it executes just a single instruction: b .