#Renderer (which only the PDF help actually covers, weirdly) generally isn't needed.
By Default, the Renderer will check for Vulkan, and if it isn't present use OpenGL or OpenGL ES depending on the platform.
Given however that Vulkan is more-or-less just a Vulkan implementation of the OpenGL 2.0 (which itself is stripped down to only support what OpenGL ES 1.1 does) ... honestly, there isn't really much difference in whichever you use.
In fact I'd argue because of the Variant of SPIR-V they're using to convert GLSL to SPIR-V... it's actually a little more reduced functionality than in AGKv2.
At least that what I've noticed.