It has been suggested that Starlink satellites might provide service to Tonga during the current Volcano eruption emergency.  Regrettably there is no terrestrial hub site sufficiently close to Tonga connected to a working sub-sea cable and the idea of using intersatellite laser links (ISL) across via several satellites and down to terrestrial hub sites in say New Zealand or Australia is not yet feasible as laser ISLs are novel and I think only some of the latest satellites may be so equipped. 

There is the alternative of High Throughput Ka band capacity on Kacific satellite if contract can be agreed. See Kacific coverage at the bottom of this page: https://kacific.com/ Click on Tonga to get an expanded view.