Gurm Deep within the depths of the 10.14 installer DMG.
(Still on 10.11 here, looking to upgrade soon because 10.11 is getting long in the tooth.
jtl-macbookpro:AMDFirmware jtl$ pwd
/Volumes/jtl/10.14 firmware/extract/Scripts/Tools/AMDFirmware
jtl-macbookpro:AMDFirmware jtl$ ls
total 472
drwx------ 1 jtl staff 16K 20 Sep 21:27 .
drwx------ 1 jtl staff 16K 20 Sep 18:13 ..
-rwx------ 1 jtl staff 179K 17 Aug 15:47 AMDvbiosupdater.efi
-rwx------ 1 jtl staff 2.9K 20 Sep 21:15 AMDvbiosupdater.efi.j132ap.im4m
-rwx------ 1 jtl staff 2.9K 20 Sep 21:15 AMDvbiosupdater.efi.j137ap.im4m
-rwx------ 1 jtl staff 2.9K 20 Sep 21:15 AMDvbiosupdater.efi.j680ap.im4m
drwx------ 1 jtl staff 16K 20 Sep 18:13 Payloads
I'll see if I can find anything else interesting.