I've gone back and done some quick calculations.
Assuming for now that the Anand A55 power data on the SD 855 is completely correct and that it uses the N7 TSMC process I inferred a 30% power reduction to N5 to normalize process node to the A14's efficiency core.
SD 855>888 A55 is ISO frequency already.
For int workloads that turns 320mW to 224mW, about 50.9% the average power of Icestorm in int workloads.
The int performance increase of IS over A55 is 20.03 from 5.42, not quite 3.7x but we'll round it up for ease of computation.
That's 3.7 x 0.509, about 1.88x for the efficiency difference between Icestorm and A55 on ISO process, unless my own math is completely out of whack?
A wide gulf to be sure, but far outside the exaggerated claims of Anand.
Again, all assuming that the power data for the A55 is accurate.
I'd like to see it measured using one of the S905X3+ SBC's on a pure Linux OS, minus the Android kludge.
It wouldn't be reflective of a battery constrained scenario, but at least it would be a pure A55 system to take readings from.
Fuchsia OS would also be an interesting power bench target now that it has finally launched - it will be interesting to see if Google have improved efficiency much over Android.
As an addendum I added the 20% efficiency gain ARM projected for A510 vs A55 at ISO process node.
Which gives us 1.505x efficiency for Icestorm over A510 on ISO process, though admittedly I'm not sure I calculated that correctly.
Edit: I used average power in mW rather than joules to calculate the int compute efficiency difference, so 1.88x becomes 1.93x - still well below 3x, let alone 4x efficiency.