On an adjacent note, the work being done/posted by Collabora motivated me to try to get Mesa + Gallium soft pipe working with emscripten. Here is a demo of the classic glxgears: https://martinmullins.github.io/mesa-softpipe-emscripten/

That is gloriously perverse!

The official binary Vulkan drivers for Mali IP have been fairly buggy for a while (especially comparing to Adreno), it's somewhat of a shame that it's not possible to bundle open Mesa drivers built for Android with an app due to the dynamic linker's enforcement of an "only use supported APIs" policy through namespacing.

Is this the GPU the one found in the Pinephone?

No the panfrost drivers only target Mali 6xx (also know as Midgard) and later GPUs.

I highly doubt the Mali 400 has the hardware required to support Vulkan.

Mali 400 cannot even support OpenGL ES 3.x, forget about Vulkan on that hardware. Mali-400 is old enough to have separate vertex and fragment shader cores.

Yes, Mali 400 GP2 is used in the Allwinner A64 for the PinePhone

Does it also support the Mali 400 GPU in Allwinner H3 based boards? There's a huge load of them around, and they are really cheap.