Nothing yet, unfortunately, as far as MagicBands/ being able to plan FP+ in advance using MDX.
HOWEVER, we still have the ability to obtain same-day FP+ with our AP cards like other day guests. The only issue is that kiosks aren't accessible all of the time and they often have long lines now that legacy FP are gone.
The only way to cheat the system at this point is to get a room ressie, even if only for a night, and link it to MDX so that you are offered a MagicBand like any other resort guest. When you link your band and AP to your account, the band can be used for admission and FP+ until the AP expires (I'm assuming that if you renew, it will also stay valid).
I was lucky enough to get a band because my mother came down to FL for a quick trip a couple of weeks ago. My local friends do not have MBs yet, and this makes it quite inconvenient to sync everything up...here's hoping Disney hurries up with the process soon.