Feature request for Mk V: An onboard committee of three atomic clocks to ensure proper uncertainty estimation when GPS is lost.
[0] https://www.microchip.com/en-us/products/clock-and-timing/co...
(Don't worry, I know they are considered atomic clocks, I have 2 Rb modules.)
Those chips are also useful for getting better positions from navigation signals. One could imagine using them to help filter out spoofed signals, for example.