There's nothing in NVMe that's inherently architecture-specific, and
NVMe should be usable by non-x86 architectures.
Nope, haven't tested it, don't have a NVME card to test with. There have between people expressing a desire to use it on PowerPC. Regardless, it should be usable on any little endian platform, and any bugs for big endian can be squashed as they are tested.