Marshmallow is 6.0, Nougat is 7.0, Oreo is 8.0.
Those are the versions of Android that support making an SD card set as "Internal" storage. That said, many manufacturers have also changed the versions that are on their devices so that you cannot make said change.
And, actually, whenever I personally share instructions about making the change, I include the info about it being encoded now. Meaning not only can it not be read by any other device, but when it makes the change it will wipe anything that was on the card before you did this.
Android Versions....
https
/en.wikipedia.org/wiki/Android_version_history