The M1 laptops already have Thunderbolt 3 which is 40Gb/s and actually faster than PCIe 4.0 x16 (only ~35Gb/s).
Also these laptops have 8 CPU cores (4 high performance, 4 high efficiency) and 8 entirely separate GPU cores. It's a powerhouse of multiprocessing, especially when you consider it's in a laptop that gets 20 hours of real battery life.
Powerhouse is a bit of an overstatement, especially with the GPU, which is honestly a pathetic offering for a device bearing the "Pro" name. Even still, the M1's multi-threaded performance can be topped by the cheaper Ryzen 7 4800u, which was shipping in $500 laptops long before the M1 even hit the market. It's actually kinda disappointing to me that Apple didn't take advantage of the 5nm node they spent so much time and money securing.
Also these laptops have 8 CPU cores (4 high performance, 4 high efficiency) and 8 entirely separate GPU cores. It's a powerhouse of multiprocessing, especially when you consider it's in a laptop that gets 20 hours of real battery life.