Migrate Between Different Phones with Apps & Data on MicroSDHC
This is not the Symbian era anymore, where you can have all data on an external storage and move it freely. App data resides in /data/data (which you can't access without root access) in internal storage, even if you have the apps themselves moved to SD card.

Move non-app data (e.g. media files, documents) off your SD card, have it formatted, then move them back. The card is then ready to be used as a storage only - most if not all Android 7.x phones do not offer the "move apps to SD" option anymore.

As of app data, use apps like Titanium Backup (root required) or Helium (no root required) to back them up on the old device and restore them on the new.

Note to others: it's been a while since I conducted cross-major-version backups myself (I usually wipe clean and start over), and specifically I've never used Google's cloud backup solution. Feel free to point out mistakes or make edits.