The rest like to Daven at 10
Getting OT here but the point of 10am shacharis (having said sh'ma already during brochos/korbonos upon waking) on shabbos is to get up early and learn chassidus or say the entire tehilim before davening so that you are in the proper frame of mind to daven in an inspired fashion.
Chabad yeshivos start the day with 90 minutes of chassidus before davening every day and 2 hours on shabbos.
Same goes for why Chabad allows (encourages?) mezonos before davening, so that davening isn't something to be rushed through to get to food but that food is something we eat so that we can better daven b'kavanah...