It seems that this format with RENDER_ATTACHMENT and multisampling is supported by all backends.

It maps to:

• Metal: rgb10a2uint
• D3D: DXGI_FORMAT_R10G10B10A2_UINT
• Vulkan: A2B10G10R10_UINT_PACK32

I'm not sure if it was previously dismissed (for any reason) - couldn't find a discussion about it.