You need more contact area between the anchors and wall material. So get longer anchors (longer equals more pull out resistance). Anchor can be anything really, a length of threaded rod works well if it’s thick enough and you use enough to support the load.

Also drill the hole a good bit bigger than the anchor bolt and use either regular concrete or good epoxy to set the anchor. You want the anchor to only be contacting the adhesive and the adhesive to unify with the spongy wall material. Another benefit of the larger hole is the ability to exactly level the anchor rods as the adhesive is setting.