According to the Technical Data document l (found at the Phonak Pro site) for the TV Connector, the provided “DC, stabilized” power supply is 5 VDC and 500 mA with micro-USB. The “Important notice” says “Only use the original Phonak power supply or an USB certified power supply 5VDC, > 500 mA”.
A normal USB port should be capable of supplying 5 VDC at 500 mA IF it meets the USB specifications. However, many USB devices don’t correctly follow standards. One would hope that Sony TV would meet all relevant standards but who knows …
IF the Sony ports meet USB specifications and if they follow the power state of the TV, then plugging the TV connector into a Sony port with an appropriate cable should allow the connector to power on/off with the TV.
I don’t have a Phonak TV connector - Oticon supplied a Toslink cable (plastic fiber optical cable) with my equivalent device. It isn’t needed if you use an analog input to the TV Connector. The Phonak TV Connector accepts both Toslink and Analog (3.5 mm plug) according to the datasheet. In my case, Oticon recommends Toslink if available rather than analog input.