I don't know that that's a fair comparison. Just because it's an ARMv8 chip doesn't mean it's directly comparable to what's in smartphones. (I assume you aren't comparing it to Apple made chips for iPhone specifically, since then it wouldn't be true that it's in "basically every smartphone in the world".)
In particular, this is the first 5nm chip to be widely available, and by most accounts on performance it competes with top of the line hardware at a small fraction of the power use. Most existing ARM chips are designed for the very-low-power market, e.g. in phones, not to be used in a high performance laptop.
If there's a Dell or Thinkpad laptop with an ARM chip that's comparable, by all means, let me know.
AFAIK you are correct. Apple has completely redesigned their own ARM chip. It has the same instruction set (or a superset of the instruction set) as what runs in a cellphone, but the design is completely different from say, Qualcomm chips.
In particular, this is the first 5nm chip to be widely available, and by most accounts on performance it competes with top of the line hardware at a small fraction of the power use. Most existing ARM chips are designed for the very-low-power market, e.g. in phones, not to be used in a high performance laptop.
If there's a Dell or Thinkpad laptop with an ARM chip that's comparable, by all means, let me know.