The first iPhone had a fixed function graphics pipeline and 2G cellular service. Unsuitable for the native application market that they set up afterward and changing cellular capabilities and customer expectations.

The first iPad was similarly very constrained, though slightly better. For all practical purposes, it was a blown up iPhone 4.

I suspect, given the general advancements and recent stability in Apple's ARM SOCs, that this first generation of hardware will be good, though maybe a bit underpowered compared to what people are used to with the Intel equivalent. But not the practically beta level of those other devices.

This doesn’t match Apple’s claims and demos of performance of emulated x86 applications. I’d suggest you watch the WWDC 2020 keynote video for more on this and take a look at the compute and graphics intensive x86 applications they demonstrated running (emulated on Rosetta 2) on ARM hardware of undisclosed specs.