We are relatively new to the Switch and to ACNH, and we are having trouble figuring out the nuances of making connections with others and the greater world. We found the 3DS and ACNL more intuitive, and with the Switch it seems like paid membership with Nintendo Online is a necessity. We've been playing ACNH for about 90 days now, and we're looking to chat/trade/extend our play. We (my daughter and I) just got connected to the Nintendo Network today, and we have our account set up on the Switch (hers is supervised but with no restrictions on communication). Maybe we just need to start finding new friend codes, but we've got some questions: 1) We'd love to reconnect with 3DS/ACNL friends who made the jump to Switch before we did. Is it possible to contact/transfer our 3DS friends who are already on the Switch? She thought she saw such a feature on the Switch... 2) Can you use the customization resource in Able Sister's without joining Nintendo Online?
"1) We'd love to reconnect with 3DS/ACNL friends who made the jump to Switch before we did. Is it possible to contact/transfer our 3DS friends who are already on the Switch? She thought she saw such a feature on the Switch..."
It is, yes! You'll need to connect your Nintendo Network ID (used on the 3DS) to your Nintendo Account (used on the Switch), if you haven't already. The naming makes this a bit confusing, but Nintendo has a tutorial explaining how to do it on their customer support website.
Once you've connected your accounts, you can go to your profile on the Switch and select "Friend Suggestions" followed by the 3DS icon. That'll give you the option to send a Switch friend request to anyone on your 3DS friends list (as long as they have a Switch too).
You'll need to do this separately for your own account and your daughter's.
"2) Can you use the customization resource in Able Sister's without joining Nintendo Online?"
You can create your own custom designs in the game without buying a Nintendo Switch Online subscription. I'm told that you can also use the Nintendo Switch Online smartphone app to import custom designs from ACNL without a subscription, although I haven't tried it myself. But you will need a subscription in order to share your designs with other people or download designs made by anyone else.
There's no place like 192.168.0.0/16.