I don't know when the project started, but ViaSat has been working toward constellation service of their own for at least 6 years: https://www.viasat.com/space-innovation/satellite-fleet/vias...
ViaSat-3 is a geostationary constellation of 3 satellites, which I don't really consider to be a competitor to Starlink due to its physical inability to ever reduce the latency lower than 500ms
Except the laws of physics I guess. Geosynchronous orbit is about 36,000 km out so best case scenario if you were going straight up to a satellite in such an orbit and back down even at the speed of light in a vacuum that’s a lower bound of a quarter of a second of latency. So unless these legacy satellite internet companies launch LEO constellations of their own, which there’s no indication they’re capable of doing, it seems pretty hopeless for them.