I watched the whole video, thanks. TBH I couldn’t find anything at all useful in there. It’s a pretty crude DIY thing. Doesn’t actually measure real power (Watts - what your meter reads), it measures apparent power (VA). If that’s all you want, you should probably just get an Emporia Vue. It uses an ESP 32 and also measures VA rather than Watts (IoTaWatt measures both Watts and VA as well as VAR).
If you want an inexpensive unit to measure Watts, the emonTX is probably a better choice it’s inexpensive and requires less programming. But if what you want is a DIY project, maybe this fits the bill.