The sysnand is encrypted with a unique serial number for your Switch only so if you got yourself blocked by going online with your emummc, then also your sysnand will be blocked.
Afaik, it is not possible to change that serial number.
But why would you need to go online with Animal Crossing?
You can get all updates for it from *cough* some sites *cough*.
You can even play with other users on local play (you might need to update to the latest version for that).