Hi,
Vulkan + Wayland is not a use-case tested in the release, so it is possible it does not work properly. Since nveglglessink is open source, you may look at the source source code and check further. The source code is in
https://developer.nvidia.com/embedded/l4t/r32_release_v7.2/sources/t210/public_sources.tbz2
There is an issue about compiling the source code. Please check
Jetson/L4T/r32.6.x patches - eLinux.org
[gstreamer] fail to build libgstnveglglessink.so