The functional equations for Dedekind zeta functions (zeta functions attached to rings of integers in algebraic number fields) come from functional equations of theta functions like $\sum_{n \in \mathbb{Z}} q^{n^2}$, where $q = e^{2 \pi i z}$, which in turn come from the Poisson summation formula for lattices in Euclidean spaces.

The functional equations for zeta functions attached to curves over finite fields come from the Riemann Roch theorem and Serre Duality (see, e.g. Chapter 2 of Sam Raskin's write-up).

Rings of integers of algebraic number fields and curves over finite fields are analogous, (see, e.g. Jordan Ellenberg's discussion of Weil's three columns).

Is there a known uniform proof of the functional equations that covers both cases?