Pulsars, magnetars and Fast Radio Bursts (FRBs) are radio transient phenomena at the forefront of modern astrophysics, serving as superb laboratories for testing fundamental physics. Recently, pulsars provided evidence for the existence of a gravitational wave background. Although we do not know FRBs origin, their highly energetic bursts emitted at extragalactic distances make them powerful tools for cosmology. Some progenitor scenarios for these sources include magnetars orbiting black holes, raising the question of whether FRBs could be originated by extragalactic magnetars. In this work, we use the Galactic Centre data from ALMA in phased mode targeting Sgr A*, to study the physical properties of their closest magnetar and link them with the ones for FRBs. We studied the energy behavior of the source at high radio frequencies and compared them with other radio transient sources. We also determined that 100+ pulsars and 18+ FRBs could be detected using ALMA in phasing mode with its newly installed Band-1 receiver, covering frequencies below 50 GHz. The prospects of detecting these sources with ALMA hold the potential for a better understanding of their emission physics: for FRBs to potentially reveal their progenitor scenario and for pulsars it could reveal the pass from coherent radio to incoherent.