> A vector instruction set that reduces pain of head/tail handling is a pretty big deal for human-written code as well.

Is there some way to automatically convert SVE2 code to slower NEON code so that you don’t have to write two versions?

If code was autovectorized, it would be easy to make two different executables, one for SVE2 and one for NEON. If SVE2 code was written by hand, there would be no way to run the SVE2 code on an older device without SVE2. No one wants to write two different versions by hand, one for SVE2 and one for NEON.