Drawing A 2D Capsule (Same of CapsuleCollider2D)

It's a little late but never too late for necroposting. You can fiddle with this code. It should support different directions and rotation however it will not fit perfectly capsules with strange proportions (ie. horizontal size.x=1 size.y=4)

 CapsuleCollider2D cc = GetComponent<CapsuleCollider2D>();
 if (!cc) return;
 
 Gizmos.color = Color.yellow;
 float step = 0.2f;
 float r = Mathf.Min(cc.size.x, cc.size.y)/2;
 float d = Mathf.Max(cc.size.x, cc.size.y)/2-r;
 Vector3 lp = Vector3.positiveInfinity;
 for (float a=-Mathf.PI; a<=Mathf.PI+step; a+=step) {
     float x = Mathf.Cos(a);
     float y = Mathf.Sin(a);
     Vector3 np = new Vector3(x, y) * r;
     np += (cc.direction == CapsuleDirection2D.Vertical ? Vector3.up : Vector3.zero) * d * Mathf.Sign(y);
     np += (cc.direction == CapsuleDirection2D.Horizontal ? Vector3.right : Vector3.zero) * d * Mathf.Sign(x);
     np = transform.TransformPoint(np);
     if (lp!=Vector3.positiveInfinity) Gizmos.DrawLine(lp, np);
     lp = np;
 }
 

You could do a rough version using two spheres (Gizmos.DrawWireSphere)

For a more elegant version you could essentially recreate the capsule collider gizmo by utilizing UnityEditor.Handles (Handles.DrawLine, Handles.DrawWireDisc, Handles.DrawWireArc)