Do the Power Pins that are not used externally like VDD_CORE, VDD_MPU, and VDDS_DDR need to be connected to the PCB?

These power pins are driven by the TPS65217C PMIC and are used internally to power the AM335x, DDR and other components.  These pins are all connected within the SiP and should not be connected externally.  Optionally, these pins can be brought out as test points for debugging purposes only.  They should NEVER be used to power external components.