Installing and using vulkaninfo
Vulkan has a standard set of tools available for all platforms. On Ubuntu this is available by installing the vulkan-tools package.
You can then use vulkaninfo to see detailed information about your Vulkan installation. I'd advise running it with vulkaninfo | less or piping its output to a text file as it can be large.
You can see the available Vulkan-supporting GPUs on your system in a couple of places here. For example the Presentable surfaces section has a subsection for each Vulkan-capable GPU you have.
It's important to know that a GPU called llvmpipe or softpipe is a software-emulated vulkan device. Thanks to the hard work of its developers it is possible to use vulkan without any dedicated hardware by translating it using llvm into native CPU code - but as expected it's much slower. Low-demand 3d software could still use Vulkan, but it's almost certain unsuitable for things like gaming. If that is the only Vulkan device listed, then your dedicated hardware doesn't support Vulkan, or its driver isn't properly installed and working.
If you don't even have llvmpipe, then it's possible Vulkan itself isn't properly installed (libvulkan1 and mesa-vulkan-drivers).
Finally, if you use Vulkan in 32-bit apps it uses a different Vulkan loader and Vulkan drivers, so you should install and check the 32-bit vulkaninfo in such a case.