Could just use bigger screws. For wood holes you can plug the hole with wood glue and toothpicks, then just screw your fasteners into that.

If you need more holding power, nearly anything you would use for drywall will work for this. If you are needing to get through the wood + drywall behind I would prefer flip toggle bolt.

I'm in the middle of doing this for an interior door.

Option A is to order a "slab" door. Measure the interior dimensions of your frame, and look for a slab door that matches.

Example: 30x80.

Just know, that slab doors usually require finishing.

• trimming the sides, routing for the hinges, and boring the holes for the door knob. Some doors have a limit to how much you can trim (ex. <1/4")

Option B is to order a "pre-hung" door. This is more involved since it requires you to remove the old casing and jamb, then replace it with your pre-hung door/casing. I haven't done one of these since it's cheaper and easier for me to install a slab door.