The dS/CFT correspondence was proposed more than two decades ago. However, to date, no fully controllable and universally accepted formulation of de Sitter holography has been established. Recently, a qualitatively different approach to de Sitter holography has been proposed, in which the dual quantum field theory is defined on a timelike boundary rather than on future or past infinity. In this seminar, we focus on this type of holographic models and demonstrate that they are subject to nontrivial constraints arising from holographic entanglement entropy inequalities, such as strong subadditivity.