Calibration of Power Supply

Wondering if anyone knows of a mythical power supply that could be used to calibrate power measurement ICs like the ADE7753.

On p. 74, one of the calibration routines for phase angle asks for two supply conditions, the first features at a 1.00 Power factor, followed by a measurement at a 0.5PF condition at the same amperage, etc. I'm not familiar with desktop power supplies, so I have no idea of where to start re: finding a power supply that is able to supply voltage and current so out of phase. What would be the equipment type name of such a unit?

However, for those of us without expensive power supplies (just a guess) it probably makes more sense to simply use an oscilloscope to observe the phase angle directly between the two channels and program the offset into the chip, no?

One of the interesting comments in the datasheet is that the allowable /adjustable phase angle offset range is about 0.5 degrees and that larger offsets have to be covered by external networks. Since I am not a fan of using resistors to drop line voltage to line levels, I'd prefer using a small transformer, like the the inherently short proof ERA 5480 instead. What phase angle offset range do these typically have?