Hello Baio77,
do you think it is possible to enable the Thunderbolt port?
I have already enabled it in the BIOS.
I currently have a WD15 connected to the USB-C port.
If the TB mode works, I would get a TB dock.
The touchpad buttons don't work for me either.
I am running the Dell 7490 BigSur 11.5.1.zip from Jazzoo. (with changed serial and uuid's).