Annnnnd... issue solved
Turns out I had incorrect BIOS setting - for some reason for 'Graphic Device' instead of 'Dynamic graphics' I had 'Discrete graphics' - after changing this setting brightness works, and even external monitor is detected
here's new output from lshw
:
sudo lshw -C video
*-display
description: VGA compatible controller
product: TU106M [GeForce RTX 2060 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:161 memory:c5000000-c5ffffff memory:b0000000-bfffffff memory:c0000000-c1ffffff ioport:4000(size=128) memory:c4000000-c407ffff
*-display
description: VGA compatible controller
product: CometLake-H GT2 [UHD Graphics]
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
logical name: /dev/fb0
version: 05
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm vga_controller bus_master cap_list rom fb
configuration: depth=32 driver=i915 latency=0 resolution=1920,1080
resources: irq:144 memory:c3000000-c3ffffff memory:a0000000-afffffff ioport:5000(size=64) memory:c0000-dffff
thank You for your time, closing this topic