In this talk we discuss the boundary behaviour of solutions to a class of nondivergence form equations of degenerate-elliptic type. We are interested in the study of Hรถlder growth at boundaries satisfying exterior cone-type conditions, and we focus on uniform estimates with respect to the regularity class of the diffusion matrix coefficients and/or to the parameters controlling the subellipticity. We present a potential theory approach and a maximum-principle approach depending on the assumptions on the operators. The talk is based on joint projects with F. Uguzzoni and, respectively, with F. Abedin.