Their USB charger costs 7€. From my experience: Just buy their charger and you'll have no problem. I've seen so many attempts at powering the Pi with alternative sources that suck and cause problems. 7€ is worth avoiding that.
It doesn't matter how cheap their charger is, no one should need to even buy one. RasPi botched their USB-C implementation, and the solution to that is not "buy yet another charger", it should be "we're fixing the design immediately, and it's going to cost us a fair bit but you can send your board back to get it replaced"
Mine, that can charge my gpd pocket can barely power my pi4.
I still see the yellow lightening bolt which indicates a "poor" power supply - which is just plain lying.