Characterising Exoplanets Satellite (CHEOPS) is the first ESA exoplanet space mission. The satellite carries a 30cm telescope, optimised to deliver exquisite (ppm-level) photometry of bright exoplanetary systems at optical wavelengths. CHEOPS has spent approximately 20% of its observing time during its 3.5-year long nominal mission studying exoplanet atmospheres through occultations and phase curves. As the satellite observes in a broad optical bandpass, these observations reveal the stellar light reflected by the planet, allowing us to access the scattering properties of the planetary atmosphere, key tracers of atmospheric aerosols. Thanks to CHEOPS' flexible scheduling, we were also able to follow the occultations of a number of ultra-hot Jupiters throughout several years. In this talk, I will present the highlights of the CHEOPS GTO survey of close-in gas giant atmospheres. I will focus on two main results: 1. Precise geometric albedos for a sample of hot Jupiters including the benchmark objects HD209458b and HD189733b, and their connected population-level trends. 2. Planetary day side variability, highlighting in particular two objects in our sample for which we observed an evolution in the planetary emission on weeks to years' timescales. I will conclude with an outlook on CHEOPS' first extended mission and on the strong synergies between current and future space-borne exoplanet observatories.