Update on the issue. Reached out to dxvk and with their help I managed to get dxvk games working:
Overall, it seems Vulkan driver selects the wrong GPU. With DXVK I can thankly specify the GPU by using this launch param:
DXVK_FILTER_DEVICE_NAME="RTX 3080" %command%
Sadly according to them, this should be a issue with the vulkan-driver itself thus it would affect all Vulkan applications and most of them don’t allow to select the GPU so that’s an issue that will stay in the air. Might look into this in the future: https://github.com/aejsmith/vkdevicechooser