Unfortunately I can’t speak to troubles with debian or the current efforts to revive coreboot support. I’m following the Heads github issue #719 - Re-upstreaming and maintainership of the KGPE-D16
At the time I read your message, the latest comment says there will be a meeting Monday 23rd August 15:00 UTC on https://meet.3mdeb.com/kgpe-d16-refresh
I also added a HCL report for the Asus KGPE-D16 (6386SE) with stock firmware here.
Best regards…