> Is learning OpenGL pretty much inevitable as a precursor to learning Vulkan?
Well, maybe not OpenGL, but almost surely some graphics API which allows you to do graphics without a couple thousand lines of obscure boilerplate.
There are lots of "middleware" systems built on Vulkan that are WAY friendlier than raw Vulkan. They handle things like asset loading, memory management, and scene composition for you. If you want to build something, use those. You'll be vastly happier at the end of the day. Maybe at some point you'll hit a performance bottleneck--fine, but by then you know a lot more about graphics.
If you're doing raw Vulkan, you should have a darn good idea as to your purpose.
If someone says: "I want to use Vulkan." I ask "Why?"
If they say: "Because I want to make a thing that does <X>." then they absolutely should be in a middleware system and not Vulkan. They'll get something on the screen much faster and keep their motivation going.
If they say: "Because I want to learn" I have to try to redirect them to something a lot simpler. Learning is about motivation and Vulkan boilerplate saps your motivation really hard.
It also doesn't help that Vulkan development is basically C++ and Windows and there is no negotiating this as a beginner. Trying to develop Vulkan through a language wrapper or on Linux/OS X adds an unnecessary amount of pain to the process--quadruply so if the wrapper tries to be "idiomatic" in your language of choice.
If they say: "Well, we found a bottleneck using RenderDoc and we..." then I ... HA! I'm kidding. Nobody says this because they KNOW why they need to use Vulkan so they don't even ask me.
The primary problem with Vulkan is that you are mapping REALLY closely to the underlying hardware. If you don't understand what the pieces of your graphics card are and what they are doing and why, Vulkan makes very little overarching sense.
One thing I will warn you about when programming Vulkan, you better be really good in your programming language of choice. There are times when you are writing Vulkan code where you have to add a couple hundred lines of code before you can finally test that you got it right. You have to be very confident in your programming skill that you got all the essential things in your language right so that any bug is really in the way you are using Vulkan. For example, if your understanding of pointers and pointers-to-pointers isn't rock solid, you're gonna have a bad time.
However, if you still wish to persist. Here is a class at Oregon State that does Vulkan:
http://web.engr.oregonstate.edu/~mjb/vulkan/
Note that this is considered an upper division/graduate class. That should give you an idea of what you're in for.