In this work, we present two recent developments in goal-oriented error estimation applied to finite element simulations. The first one is a non-intrusive enrichment of the adjoint solution using handbook techniques, inserting locally the (generalized) Green functions associated with the quantity of interest under study. The second one is a new bounding technique, based on homothetic domains, that is an alternative to classical Cauchy-Schwarz boundings. Technical aspects and capabilities of the resulting verification tool will be shown on 3D numerical experiments.