Android does support Vulkan. Although I don't think you can do graphics from outside the main thread, which is a major feature of Vulkan. A key idea in Vulkan is that the main thread is just doing refreshes, while other threads are changing what's in the GPU. This allows keeping the frame rate up even when the scene is changing.

(We've had a split on concurrency. Web devs think in terms of callbacks and async, but not real multiple threads running on multiple CPUs with explicit locking. Game devs doing high performance games think in terms of multiple CPUs and the GPU all working in parallel, pumping huge amounts of graphics content. WASM and Android follow the web model. There's kind of a hack involving multiple processes with some shared memory, but it's not general purpose threading.)

It would be interesting to see some data on how good the Vulkan support coverage is. And early Vulkan devices may have buggy or poorly performing drivers.

Apps usually go for the API that works on all devices.