I discuss the testability prospects of the minimal GeV-scale type-I seesaw model and the associated leptogenesis mechanism within future experiments as SHiP and FCC-ee.
In particular, I show how to derive accurate analytical approximations to the solution of the kinetic equations, which expose the non-trivial parameter dependencies in the form of first principles CP invariants. On the one hand, this allows to derive robust mass-dependent upper and lower bounds on the HNL mixing. On the other hand, it also reveals the correlation of baryogenesis with other observables, as e.g. the flavour structure or neutrinoless double-beta decay.