Yes, you are correct, at one time using blank NFC tags was considered the best method.
The big difference is the little unit I described is ready to go, the only thing you need to know is the amiibo number for the character you want if you do not want to edit the file names. They have a chart with pictures to look up the character, but it follows the same as the regular amiibo. For example, Avery is 140, you scroll down to AC 101 -200 and in that folder select AC 140.bin and hold the unit near the pro controller and it calls Avery. It is really fast at Harvey's Island doing group pictures.
I think they have every amiibo currently available already in this newest system, but I only know about ACNH , and it seems complete . I have no experience with the amiibo characters for the other games, we only play ACNH.
Very nice puzzle! Your review was a great addition. I like both versions, thanks for sharing. It looks like a great place to visit.