@zdavatz As Leigh pointed out, you’ve by the looks of it been running with the open-source driver, Nouveau, before. If that has changed in behaviour, upgrading to 5.6, then there’s been some kind of change in the kernel that broke it. That’s something for either your distro’s (Funtoo?) bug tracker, or even kernel upstream.
If, however, you want to try the proprietary NVIDIA driver, then that’ll have to be patched first – it’s not compatible with 5.6 as-is. There’s already been a post on this forum on this issue here, and this seemed to have soled the issue of building the driver.
Personally, I’d recommend holding off with upgrading – staying on the 5.5 branch for now – and continue to run with the Nouveau driver, if that has worked without issue for you before. That, and to report the breakage to your distribution.