That's not entirely accurate. There are a lot of ARM CPUs that are not vulnerable to Spectre, and that includes a lot of them that are in use in actual devices. For example, my phone happens to use a Cortex-A53, which is not vulnerable. It is however easy to miss this detail from their 'security update' [0] because the table doesn't list CPUs that aren't affected.

Also, I don't believe the single ARM CPU that's vulnerable to meltdown (Cortex-A75) has actually been included in any devices at this point, so for now it is safe to assume any ARM-based device you have is not vulnerable to meltdown.

[0] https://developer.arm.com/support/security-update

I believe Apple's ARM CPUs are vulnerable to Meltdown.

Not the Watch though. Apple, as expected, hasn’t said why.

Probably because its a much simpler core like all the other chips that are immune. It simply doesn't do the the logic that would get the chip in trouble.

That is because a lot of ARM cores don't have out-of-order or speculation capabilities.

AMD CPUs are completely unaffected by Meltdown, since AMD checks permissions before fetching memory into the cache.

It's really impressive that AMD CPUs are as fast as they are given that this is the case.

This is now at -1 and I am extremely confused as to why.

Some ARM CPUs are vulnerable to Meltdown:

https://developer.arm.com/support/security-update