Heat treatments of Me2O-Ga2O3-GeO2-SiO2 glasses (Me=Li, Na) result in bulk precipitation of Ga-oxide nanocrystals (NCs) and give rise to nanostructured optical glassceramics. Here we show how luminescence can be tuned by changing the number of acceptor and donor sites, size and volume fraction of NCs, doping and thermal treatments. Light emission of Ga-oxide NCs in alkali-germanosilicate matrix can be changed from blue luminescence of undoped systems to UV and IR emission of Ni2+-doped samples, while TiO2 addition leads to white light generation. We also demonstrate that bulk glass can be used to produce targets for sputtering deposition of films on conductive substrates, enabling the fabrication of light emitting devices with electrically driven UV/blue/white emission. The results provide a guideline to design multifunctional nanostructures based on wide-band-gap oxides with a potential as materials for broadband amplifiers, solar-blind UV-to-visible converters and UV sensors.