Røde’s website says it requires 15V 2A USB-PD support (30W) so it probably can’t be bus-powered by an iPad.
What I’ve read suggests that they can deliver up to 7.5W to accessories (presumably 5V 1.5A), but I haven’t been able to find an official source from Apple for that.
The device seems expensive for a six channel mixer/interface, but maybe its specific features and form-factor are worth paying extra for, depending on the setup.
As an alternative, the Zoom L8 is half the price here, has two more channels, and looks like it could even be bus-powered by an iPad (5W).
And the L20 still costs less than the RodeCaster.
I don’t think there’s complete overlap in the features, and the L8 is certainly going to look worse in a desktop setup; but these are just a couple of examples of the options out there.