Any offsite guest with a TICKET can pre-book Fp+ 30 days in advance if they have linked it to a My Disney Experience account.
A MagicBand is not a necessity - it is equivalent to a hard, plastic ticket for offsite guests.
Having a My Disney Experience account with a ticket linked to it gives anyone the ability to pre-book Fp+.
The only guests who have to book day of Fp+ are those who buy their ticket right before they enter the park. CMs also have to wait to do day of booking.
Is this brand new?? I've been stressed about being offsite and having to stand in a crazy long FP kiosk line every day at the parks. This will be great!
It begins tomorrow!
Bill