In relativistic heavy-ion collisions, a quark-gluon plasma (QGP) is created. Its pre-equilibrium evolution includes a rich variety of exciting phenomena of Quantum Chromodynamics (QCD). Understanding the initial stages of the pre-equilibrium QGP is also necessary for the phenomenological analysis of heavy-ion collisions. In this talk, we delve into some of the less understood aspects of the pre-equilibrium QGP dynamics. Specifically, we explore nonperturbative collective excitations, universal dynamics, and strategies aimed at deciphering the initial stages using experimental probes such as jets and heavy quarks. If time allows, we will also discuss our recent efforts towards developing a general ab-initio method for real-time dynamics of QCD based on Complex Langevin equations. Through these discussions, we aim to shed light on the fundamental properties of the QGP and its implications for high-energy physics.