The talk covers the enabling power of hollow-core photonic crystal fibers (HC-PCF) and their functionalized form Photonic Microcells (PMC) by showing how the association of glass, gas and light has created several paradigms in fields as different as photonics, nonlinear and high field optics, cold atom and laser metrology, and plasma physics. I start by reviewing the principle of optical guidance in Inhibited-Coupling HC-PCF which led to ultra-low loss hollow fibres, and highlights its enabling power in handling light and gas in extreme situations such as ultra-high energy laser handling, multi-octave optical comb generation, single-cycle pulse compression, in-fibre plasma generation, and cold atom harboring in micro-structure photonic components. I will then finish with an intriguing yet powerful way of nano-structuring molecular gas using a recently developed Lamb-Dicke regime of stimulated-Raman-scattering. Here, hydrogen molecules inside a photonic bandgap hollow core fibre are deeply-trapped in self-nanostructured optical lattice to emit watt-level CW Stokes-radiation with sub-Doppler resolved spectral sidebands and with a sub-recoil linewidth as low as ~3 kHz, which is ~6 orders-of-magnitude narrower than what conventional stimulated Raman scattering predicts. This new route of trapping molecules could open new paths in several fields such as trapping and cooling molecules, or manufacturing of gas nanostructures such as micro-mirrors and micro-cavities as we do with solid-state materials.