You made it hard on yourself. I went from a 128gb card to a 256gb card and all I had to do was format the SD card and copy the folder over
performed same steps from the Nintendo site, when I inserted the new card into the switch after copying from smaller to my 512. It said it it could not use the new as card. Also when attempting to put old card back it it said it couldn't read that either. Will be a scary day when time comes to migrate to switch pro... I would suggest getting a one month Nintendo online to back up saves to be safe. Glad I had mine...