Yes, a PP-20 can handle 240VAC hot phase to neutral. To use 240VAC, you would wire the PP-20 with its 277VAC wire leads, not its 120VAC leads. Since it will actually be receiving 240 instead of the expected 277VAC, the power supply portion of the power pack will not supply the full 150 mA that one sourced with 277VAC would. This will not affect the ability to switch the 240VAC load, it only means that you would be able to power fewer sensors per power pack with 240VAC instead of 120 or 277VAC. For most applications with one or two sensors per power pack, this is not going to be an issue.
Yes, the WSD can handle 240VAC hot phase to neutral. This will not affect the operation, as the WSD does not supply power to other sensors.