400-800ppm Ga2O3 in a mineral which is a fraction of the whole...

400-800ppm Ga2O3 in a mineral which is a fraction of the whole ore, from the upgrade factor, around 25% of the ore. Chloritized schist is one which contains >50% chlorite group minerals. This is not going to be selective mining, especially under >20m of cover (0, 16 and 52m in reported holes. Are they planning to selectively mine with tweezers to get the individual grains of chlorite from 20m underground? Schists don't make for stable underground mines, so it'll be open pit.

As to the mythical "simpler and cost effective" process, better than which process? There is a good reason there are no Ga mines, the costs are far too high unless the grade is much higher than here or are in a mineral which is very readily concentrated, e.g. a sulphide. The current mines only recover it because it's a comparatively low cost especially once the mining and other processing has been covered my the main element. Even for bauxite processing, where the costs are probably the lowest given the value of the smelter grade alumina product, it's not economic to recover unless the sales price is somewhat higher than the Chinese will drop it to before the mine even starts processing.

Even by a magical mining method and a mythical recovery process the costs of producing the required product will be higher than any existing producer. Too low grade, too deep and no low cost recovery method.