Trigger collision with object A, real collision with object B

In a simple 2D game I’m making to get used to Unity I have a small issue for which I couldn’t find a nice solution so far:

I have a ground object with a BoxCollider2D and a player object with a Rigidbody2d and also a BoxCollider2D. So far so good, the player can move on the ground without falling through.

Now I have enemies which I want to shoot down - also easy. BoxCollider2D (Trigger) on the enemy and my bullets and everything works fine. However, after being killed enemies drop some debris which I want to collide with the player in trigger mode but still stop when touching the ground object.

Is this somehow possible?

TL;DR: I want an object to trigger-collide with some objects and have a proper collision with another object.

Give the debris object a Rigidody2D, a regular collider, and a child object. On the debris-child object, create a trigger collider.

Now, set up some collision Layers. Maybe six, one each for the Player, Enemy, Bullets, Ground, and Debris, and Debris-Child. (You can probably accomplish this with fewer.) Now, the Player Layer needs to collide with the Ground and Debris-Child, but not Debris. Debris needs to collide with the Ground. And of course Bullets and Enemy need to collide. (Other combinations are up to you - do you want Bullets to be stopped by Debris?)