In the
Fextralife livestream, at 02:26:28, you can see the damage of Flurry of Blows being 8-18 (1d6+3+1d6+3).
We can calculate the level from his health being 24.
8+2+(4.5+2)*2 = 23, so we know his level is 3. This can be confirmed by the health of the other companions as well.
Since it is flurry of blows, he is attacking with his fists and dealing his monk damage die. So while sometimes monk weapons may deal more damage than the monk weapon die, and you can CHOOSE to deal your monk weapon die in damage, you don't have to, this is not the case here.
Meaning at level 3, monks have a monk damage die of 1d6, suggesting they start at 1d6 and end at 1d10 at level 11, instead of starting at 1d4 and ending at 1d8, as they would in the PhB.
Other buffs seem to be the number of Ki points, though it is still unclear to me how many exactly they get, and that they can use any weapon they are proficient in as a monk weapon, so they can in particular use stuff like Great Weapon Master.
Monk dips for other classes, so that they can use dex for damage (similar to 1lv hexblade dips in tabletop for cha) might actually be interesting for some multiclass builds

Did you fund any other buffs for the class?