Wow,

!!! Let me start off by saying: WELCOME TO THE FORUM!

...and thanks for the feedback, of course! But 8k is truly more than twice the max res I would've ever dreamed of, honestly. Besides the GPU limitation, there's still a bit of trouble with loading files that size, because Verve is still only 32bit. I would not recommend going higher than 3k with it. I'm working on alternatives, which may allow working at 4k or potentially no limit eventually, but for now it's still a bit sensitive to high resolutions.
In its heart, Verve is still a bit experimental in a way, because of its unorthodox nature, running almost entirely on the GPU with a number of buffers per image layer, which enable the complex fluid dynamics, material volume and color blending abilities. Though it is somewhat streamlined as it is, these come at a cost.

However, when the time comes and I regain the freedom to focus on taking it to the next level, dealing with high resolutions is on top of my list right after the complete GUI revamp!
I sincerely hope this won't keep you from exploring its powers and still give you some creative joy in the meantime. And I'd be thrilled to see your "First Doodle" and anything of your explorations you'd enjoy sharing here!