Addendum to “Étale dévissage, descent and pushouts of stacks” [J. Algebra 331 (1) (2011) 194-223]

Using Nisnevich coverings and a Hilbert stack of stacky points, we prove étale dévissage results for non-representable étale and quasi-finite flat coverings. We give applications to absolute noetherian approximation of algebraic stacks and compact generation of derived categories.