How can I remove a toilet brush that is deeply stuck in a shower drain?
Coathanger, cut into a wire, with a hook on the end might work.
Push the hooked end past the stuck brush, keeping the hook near the perimiter of the pipe.
Rotate the hanger 90° so the hook is under, and engages, the stuck toilet brush.
Pull up on the end of the coathanger with a pliers or vicegrips.