I am using the included DJI charger that came with my Fly More Combo. Of course, my unit being KR unit, the wall-plug was not compatible, I was super lucky to find a US wall-plug compatible cord laying around, that connects to the charger...
I don’t think the “fast” charging is much different than the usb way, in that if you are charging all 3 batteries at once they are spreading the charge between the 3 batteries. If it fast charged them in the sense that it was 1 at a time then yes...
I have the parts to build about a dozen mini whoops, there are 7 on the wall. DJI's, theres the air2s the 3 og mavics the shoebox of tellos and their remnants lol. the 3 FPV's that still see plenty of air time despite how darn heavy they are...