There are several industrial sites using 277V/480V and quite a few with 230V/400V. See this industrial 480V site.
As far as I know, all of these sites are four-wire three-phase, so the reference voltage is line to neutral (230V or 277V). IoTaWatt can “derive” everything else from that.
Your suggestion to step down 480V->240V>9V should work but the combined phase shift of two transformers may be excessive. It might be better to simply connect the primaries of two standard 240V->9V transformers in series.