I'm in.

If 100% PoS, how is made the original distribution?
Have to stake on something.

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edit:
After thinking for 2 minutes:
linking RasPi hardware to user login is very bad!
Pseudonymity is not perfect. No need to make it worst.
Linking hardware to username also link their IP and localisation.
I don't like that.

Use something NEM-like.
Earlier poster in this thread (with 10~20 minimum message) qualify for a share of the YUM (or PiNX unit).
Should not be a problem to split one's YUM in 2 to run 2 RasPi.
(It secure the network even more, perhaps. More decentralized)

I'd like OP return on this [distribution model & no-link].

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more:
You wish to rely on a single hardware IP for distribution.
Point is for everyone to receive an even share I guess.
Using bitcointalk.org login seem more convenient than hardware ID.
At worst some will start mining/printing while other await for their RasPi to arrive.
I don't see that as a big problem.

Fairness is good to have in mind, but 2 millions people at start is just not realist...
Take 1000~4000 people. Already amazing.

I hope you are serious w/skill, and not delusional.
That's a great idea.