Second monitor not detected, brightness not working... with Nvidia (GTX 1660ti) and Ubuntu 20.04 (kernel 5.4.0)

I've just bough a new Asus laptop (Ryzen 7 4800h, Nvidia GTX 1660ti), and I'm running into several graphic issues with Linux. As described in the title, so far, the issues are that the second screen is not detected (HDMI), and that the brightness control is not working at all (and it's killing my eyes lol).

I've tried with both nvidia-440 and nvidia-435 drivers, with no luck. At least, as opposed with Linux Mint, which I also tried, the cpu doesn't seem to be under heavy load with Ubuntu.

I have everything up to date and I've also used the autoinstall command:

sudo apt-get update && sudo apt-get upgrade -ysudo ubuntu-drivers autoinstall

This is the output of inxi -G:

Graphics:  Device-1: NVIDIA TU116M [GeForce GTX 1660 Ti Mobile] driver: nvidia v: 435.21            Device-2: Advanced Micro Devices [AMD/ATI] Renoir driver: N/A            Display: x11 server: X.Org 1.20.8 driver: ati,fbdev unloaded: modesetting,nouveau,nvidia,radeon,vesa            resolution: 1920x1080~77Hz            OpenGL: renderer: llvmpipe (LLVM 9.0.1 128 bits) v: 3.3 Mesa 20.0.4 

(It shows the nvidia-435 driver because that has been my last try, but as said before, it doesn't work either with 440).

Also, the Nvidia X Server Settings panel is just blank, with the "Help" and "Quit" buttons. And clicking help just says that there's no help:

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I also leave the output of lshw -c video just in case it's useful:

  *-display                        description: VGA compatible controller       product: TU116M [GeForce GTX 1660 Ti Mobile]       vendor: NVIDIA Corporation       physical id: 0       bus info: pci@0000:01:00.0       version: a1       width: 64 bits       clock: 33MHz       capabilities: pm msi pciexpress vga_controller bus_master cap_list rom       configuration: driver=nvidia latency=0       resources: irq:68 memory:fb000000-fbffffff memory:b0000000-bfffffff memory:c0000000-c1ffffff ioport:f000(size=128) memory:fc000000-fc07ffff  *-display UNCLAIMED       description: VGA compatible controller       product: Renoir       vendor: Advanced Micro Devices, Inc. [AMD/ATI]       physical id: 0       bus info: pci@0000:05:00.0       version: c6       width: 64 bits       clock: 33MHz       capabilities: pm pciexpress msi msix vga_controller bus_master cap_list       configuration: latency=0       resources: memory:d0000000-dfffffff memory:e0000000-e01fffff ioport:c000(size=256) memory:fc500000-fc57ffff

And also the output of lspci | grep -A 1 -i vga:

01:00.0 VGA compatible controller: NVIDIA Corporation TU116M [GeForce GTX 1660 Ti Mobile] (rev a1)01:00.1 Audio device: NVIDIA Corporation TU116 High Definition Audio Controller (rev a1)--05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Renoir (rev c6)05:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Device 1637