That's a clever idea. Instead of removing and replacing a faulty PMIC, he's using a PMIC from an identical donor and hardwiring its outputs into the patient. An alternative approach would be to hardwire one or more DC-DC converter modules, but then you would have a potential problem with power-up sequencing.
Years ago I had the same idea to power up the MCU on a WD PCB where the SMOOTH IC was burnt. That is, use the voltages from a donor PCB to power up the patient MCU and then read its embedded ROM via terminal. The problem is that one would need to ensure that the POK signal was set, but I don't know which pin this is. This could also cause problems with those PMICs that have Power_Good outputs which are sensed by the controller, or those PMICs with an I2C bus that communicates with the controller.
BTW, here is the "embedded" URL, if you want to avoid Youtube's fluff:
https://www.youtube.com/embed/uaKWK5IH7xcI've been watching his other videos. There's a lot of good stuff there, although I don't agree with some of his methods.
This is the RSS feed for his Youtube channel:
https://www.youtube.com/feeds/videos.xml?channel_id=UCrHVBycuv9_EUQmHQOEotQA