NVME showing as external

[zoki bajatovski]

M.2 drive showing as external
catalina gigabyte b450m ryzen 2600 GFX rx 5500 xt

 

[H4L9000]

Add a device property as "built-in" with data 01000000 to your config.plist and reboot - then it will show as internal.
You need to find your correct PciRoot path, e.g. with use of Hackintool in the section PCIe.