Without such venture capital, I doubt GPUI, at least to the level of complexity it has today rather than being a toy project, would have even existed. It costs money to develop open source sustainably.
IMGUI and other GPU accelerated toolkits exist and have been created without billons of VC revenue.
In fact the entire Qt group is just work 650m EUR
GPUI development predates Sequoia's funding by about two years.