@Asxetos:
Welcome to the Win-RAID Forum!
AFAIK the NVMe BIOS module, which is required to be able to boot off an NVMe SSD, is not manufacturer specific. So this module should support all NVMe SSDs from all manufacturers.
If you are able to boot off a Samsung PM961 NVMe SSD, the Toshiba NVMe SSD should work with the same system as well.
The name of the SSD may not be visible within the BIOS, but it will be detected nevertheless. After having successfully installed Win10 onto the Toshiba NVMe SSD, the related entry within the BIOS will be "Windows Boot Manager".
Good luck!
Dieter (alias Fernando)

@Asxetos:
You are right: Since the BIOS of your Dell notebook has shown the Samsung PM961 as M.2 PCIe SSD, it should show any other NVMe SSD at that location as well.
Provided, that you haven't inserted the Toshiba NVMe SSD into one of the SATA M.2 ports, there seems to be only 1 possible explanation for your problem:
Dell has prevented the usage of any other NVMe SSD model with its notebook by having put some restrictions into the BIOS.
The question for me is, whether Dell has customized just the NVMe module or parts of the system BIOS modules.
Please attach or give me a link to the latest "pure" BIOS file (no *.exe) and I will try to find out which sort of NVMe module Dell has inserted.

@Asxetos:
I am not able to extract both files. The error message says: Access denied!

@Asxetos:
Thanks for having re-uploaded the complete dump to a hoster and posting the link.
I was able to open the BIOS file, but couldn't yet find any NVMe module, because Dell has created the BIOS without giving each DXE Driver module a certain name.
So it will take along time to extract all DXE Drivers and to look into them by using an Hex Editor.

Zitat von Asxetos im Beitrag #7

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You didn't rename them.

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@Asxetos:
Meanwhile I was able to extract the NVMe EFI module from your dumped BIOS. After having opened the BIOS with the UBU tool it was rather easy to find the NVMe module and its GUID.
The complete Nvme.ffs file has a size of 29KB and seems to be a "normal" AMI NVMe module (as the UBU tool had already stated), but to be certain, I have to compare its content with other AMI NVMe modules from rather similar mainboards. The AMI NVMe module of my ASRock Z170 BIOS has the same GUID as yours, but a completely different content and only a size of 21KB.
EDIT: The Nvme.ffs file of the latest BIOS for an ASRock Z370 mainboard has a size of 24KB, but is still smaller sized than the Nvme.ffs file of your Dell BIOS.
So until now I don't know why your Dell BIOS doesn't detect a Toshiba NVMe SSD.

Zitat von Asxetos im Beitrag #10

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Is there any possibility to simply swap the module on the 5580's bios and test?

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@Asxetos:
How did you extract both "pure" EFI modules and why didn't you attach the complete modules (with GUID)?
For security purposes please attach the BIOS of the other Dell notebook.

@Asxetos:
Nevermind, here is the link to the 5580-dump.bin file, where I have replaced the "body" of the NVMe module by the 21KB sized one: https://1drv.ms/u/s!AjMjdZ6bIhRQhI9bGrO_zPHMNa_z0g?e=ExQNXW
Good luck!