Vulkan is stuck on C API levels, requires an expertise level that many devs aren't willing to deep dive into, it is an extension fest, with Android and GNU/Linux being the major deployment targets.
On Android it is actually an optional API since version 7, so an OEM can even release an Android 9 device without Vulkan support if they so wish and the version fragmentation is all over the board.
Vulkan is stuck on C API levels, requires an expertise level that many devs aren't willing to deep dive into, it is an extension fest, with Android and GNU/Linux being the major deployment targets.
On Android it is actually an optional API since version 7, so an OEM can even release an Android 9 device without Vulkan support if they so wish and the version fragmentation is all over the board.
https://vulkan.gpuinfo.org/vulkansupport.php#android_devices
Nintendo also has their own API, NVN.