Dear professor, Landsmann,
You write
"...it may be helpful to note that in classical coin tossing the role of the hidden state is also played by the initial conditions (cf.Diaconis & Skyrms, 2018 Chapter 1, Appendix 2). The 50-50 chances (allegedly) making the coin fair are obtained by averaging over the initial conditions, i.e., by sampling. By my arguments, this sampling cannot be deterministic, for otherwise the outcome sequences appropriate to a fair coin would not obtain: it must be done in a genuinely random way. This is impossible classically, so that (unless they have a quantum-mechanical seed) fair classical coins do not exist..."
And, concluding you, state:
"I would personally expect that a valid theory of the Planck scale (including quantum gravity or string theory, though these words are misleading here), far from assuming the Born rule and the rest of quantum mechanics (as these theories normally do), would derive quantum mechanics as an emergent theory (instead, the opposite seems to be the majority goal, i.e. deriving gravity as an emergent phenomenon from quantum theory). Thus quantum mechanics would typically be a limiting case of something else, which would, then, also render the Born rule valid in some limit only, rather than absolutely."
My humble self is interested to see that we can indeed reduce this whole classical/quantum divide to an intuitive picture -- when we think of the self-referencing state (typically every mind/observer) as, by you, own "quantum mechanical seed".
That is, we can approach quantum mechanics from the perspective that it is fundamentally about self-reference such that the observer is by definition the norm/normal e.g. the unit or constant refractive index by which we are at any instance describing our cosmology. Modelled as Gödel's self-referencing state, every mind simply is thus the quantum of own observables (typically the probe energy or beat frequency or quantum vacuum) if the Landauer limit.
This will be just in the exact same way that Planck's quantum (v = E/h) is that norm/normal by which in spectroscopy we are attempting to describe the applicable black-body radiation as a unique arrow of time (the black body spectrum).
In this sense every mind would be as the phase constant own Kolmogorov incompressibility (own energy/time or wave/corpuscular uncertainty threshold); just what the constant refractive index is to all observable dispersion relations of light i.e. to all self-referential splitting of light into constructive versus destructive interference; perhaps your binary string.
Hoping that you can take a look at how I grapple with this vision (being an editor, please don't let poor wordings distract you).
Chidi Idika (forum topic: 3531)