As I mentioned, the handshake has everything to do with the system you are connecting too and cable you use. These are not 'hardware' issues. It is entirely a software based decision.
With the same cable iPhone 15 Max and the iPad Pro M2 have the same connection to a computer. You get a slower handshake because that has been decided best for compatibility, stability and charging. Regardless, both are transferring data at decent speeds that keep the devices cool.
Apple could update the software to enable a faster transfer on iPhone and iPad but then we still going to see complaints in one form or another. 'Oh now the transfers are so fast my phone gets hot' etc etc.
Here below the iPad Pro M2 with the Apple Thunderbolt/USB cable. As you can see there is nothing wrong with the iPhone 15 Pro/Max hardware as this discussion has been stipulating. Why doesn't the iPad Pro have a 40 Gbits Thunderbolt connection? Why is it USB? It has been like this for a long time. iPad Pro owners were not pulling their hair out and going mad about it.
Regardless, when you connect an SSD or other devices to the iPhone Pro/Max or iPad Pro it will operate as it should.
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