not sure if Vulkan OK. months ago I've asked fellow mobile gamedevs and was told Android Vulkan drivers is buggy, so not really usable at practice. maybe things changed since then, I don't know.
special ? I think it was said 100x times already - PowerVR2's per-pixel translucency sorting, neither of modern GPUs have such feature.
but it may be simulated, by rendering fragments to (huge) linked list buffer, OGL's ARB_shade_storage_buffer or D3D11's Unordered Access View, and then sorting these fragments in another shader. it require A LOT of GPU computing power, GPU memory amount, and fast enough access to it.
I still have doubts if latest and coolest embedded GPUs capable if that (in term of speed).