Is this assumption correct, that adding a magnetometer, accelerometer, simple GPS, etc to a motherboard would improve its entropy gathering? Or is there a mathematical/cryptographical rule that makes the addition of such sensors useless?

Do smartphones have better entropy gathering abilities? It seems like phones would be able to seed a RNG based on input from a variety of sensors that would all be very different between even phones in the same room. Looking at a GPS Android app like Satstat (2) it feels like there's a huge amount of variability to draw from.

If such sensors would add better entropy, would it really cost that much to add them to PC motherboards?

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(1) https://news.ycombinator.com/item?id=30848973

(2) https://mvglasow.gitlab.io/satstat/ & https://f-droid.org/en/packages/com.vonglasow.michael.satsta...