Looks like 2021 really could properly be the year of Wayland on the Linux desktop. For plenty it already is but NVIDIA have been a sore spot and it looks like they're moving forward now too.
NVIDIA's Erik Kurzinger has submitted a Merge Request to the xserver GitLab titled "Xwayland: Support hardware accelerated rendering with the proprietary NVIDIA driver", with the two patches included "intended to accompany upcoming support in the proprietary NVIDIA driver for hardware accelerated GL and Vulkan rendering with Xwayland". Kurzinger continues to mention that once a driver is out with the needed hooks, this code should "just start working".
The patches are being sent out to be considered, so that they can get some feedback and see if there's any substantial concerns about their approach to it.
As for the performance of it? They expect it to be "on-par with native X11 based on the benchmarking I've done", although there's "an annoying extra copy required for presentation of windowed applications, but the impact doesn't appear to be significant" and you shouldn't see it for full-screen applications as long as the compositor works with the zwp_linux_dmabuf_v1 interface.
Why is all this important? With Wayland coming along to replace X11 as a big shakeup for Linux as a whole, you need XWayland to provide that backwards compatibility to enable existing applications and games to continue working well into the future.