1. Can you provide complete dump of cbfs content which is displayed at end of make.

FMAP REGION: COREBOOT
Name                         Offset    Type          Size Comp
cbfs master header          0x0       cbfs header       32 none
fallback/romstage             0x80    stage          41108 none
cpu_microcode_blob.bin       0xa180    microcode    191488 none
fallback/ramstage             0x38e00 stage          94587 none
vgaroms/seavgabios.bin       0x4ffc0 raw          28160 none
config                      0x56e40 raw             226 none
revision                      0x56f80 raw             680 none
spd.bin                      0x57280 spd             1536 none
fallback/dsdt.aml             0x578c0 raw             8596 none
payload_revision             0x59ac0 raw             237 none
(empty)                      0x59c00 null             408 none
fspm.bin                      0x59dc0 fsp          581632 none
vbt.bin                      0xe7e00 raw             1168 LZMA (4608 decompressed)
payload_config                0xe8300 raw             1760 none
(empty)                      0xe8a40 null             856 none
fsps.bin                      0xe8dc0 fsp          189109 LZMA (212992 decompressed)
fallback/postcar             0x1170c0 stage          18352 none
fallback/payload             0x11b8c0 simple elf    68746 none
(empty)                      0x12c5c0 null       10713048 none
bootblock                   0xb63dc0 bootblock    49152 none

2. Check menuconfig or open .config in your favorite editor & check there for file name.

I can’t see anything in the .config file that references pci8086,9b41.rom - however see below...

3. This link might be of help: https://www.coreboot.org/SeaBIOS#Adding_a_VGA_option_ROM
& https://www.coreboot.org/VGA_support#How_to_retrieve_a_good_video_bios

I used the information in the “UEFI Method” section of that page to extract the VGA BIOS that I have.

4. You need not add both vbios & vbt.
Either go with vbios or with vbt.
If you plan to use Seabios as payload then vgabios should be fine.
And let SeaBios run VGA bios to init display. Refer link above on how to add them.

If you intend to go with vbt.bin then check if extracted vbt.bin is correct or not by comparing it with https://github.com/intel/FSP/blob/master/CometLakeFspBinPkg/CometLakeV/SampleCode/Vbt/Vbt.bin

I can’t guarantee that SeaBIOS will be the final payload - the end customer hasn’t specified yet. It is likely that it will need to be UEFI compatible so could end up being TianoCore. On that basis, I think I need to go down the vbt.bin file route. The vbt.bin file that I have extracted is almost identical to the one in the repo you reference. There are some bytes that are different which I assume are the timing specific information for the panel in this laptop.