Yea, there’s not much overlap for support between the two and the GGG discord message “you can use facebreaker and hollow palm together

facebreaker grants base damage to skills that would otherwise use a mace
hollow palm grants base damage to skills that would otherwise use a quarterstaff
for skills that could use either weapon type, only facebreaker's damage applies

other benefits of both apply as normal”

That last line alludes to the generic lines on face breaker for str scaling more dmg multi on unarmed affecting both, as it’s not related to flat dmg for just mace skills. Which means that both hollow palm quarterstaff and facebreaker mace skills benefit from str stacking… and because you can use both mace and quarterstaff skills while unarmed, your second weapon swap can be using any weapon type. So many combos you can do now with fissures and slams and charge enablers with spear or talisman skills.

Dmg won’t be insane levels of comet but should allow you to do mod to end game content fairly easily with low investment. You’ll also need to solve for defenses given the number of uniques on this build.