Hello Ross. Nvidia cards being an issue with gamescope is a known problem. Also, I hate invision board and my inability to inline code.
The helping bit in your log is the following (the negative integer):
Quotevulkan: vkCreateDevice failed (VkResult: -1000174001)
That's the value for VK_ERROR_NOT_PERMITTED_KHR. Reading up the documentation about it, we learn that this is returned when:
QuoteAbuse of this feature may result in starving the rest of the system of implementation resources. Therefore, the driver implementation may deny requests to acquire a priority above the default priority (VK_QUEUE_GLOBAL_PRIORITY_MEDIUM_KHR) if the caller does not have sufficient privileges. In this scenario VK_ERROR_NOT_PERMITTED_KHR is returned.
There's something going on with gamescope that makes the driver iffy about the priority requests. I'm not learned enough to know what the priority is, that is if it's a user right to tweak within the system or something entirely internal to vulkan. At first glance it ought to be internal, as it pertain to how the hardware processes go. Being able to ask for specific priorities is one of the strengths of vulkan, as it removes intermediate "framework" layers. Issue comes when the hardware/driver is a little bit hostile to it (vulkan is not a nVidia proprietary tech).