Iago Toral of Igalia has written up a blog post going over a bunch of work done for the V3DV Vulkan driver for Raspberry Pi 4 and it's coming along nicely.
Toral noted in the update how the V3DV driver has over the last few months added support for a good bunch more extensions, which means it's closing in on Vulkan 1.1 support. It's not quite confirmed yet though. Although it has all of the mandatory requirements added for Vulkan 1.1, it still needs to go through conformance testing and fix any failures that come up yet. Toral noted how "the bottom line is that Vulkan 1.1 should be fairly close now".
Quite exciting, since this means the RPi 4 will become an even more impressive unity when run with Linux and Mesa, enabling it to perform even better with games and applications that make use of the cross-platform Vulkan graphics API.
When it comes to games though, you still need to find those that do actually have Arm ports. That said, if you weren't aware there is the Box86 project which is a "Linux Userspace x86 Emulator with a twist" that does enable many x86 games to work on Arm hardware with reasonable performance too - perhaps we might even see some Vulkan support there in future too.