I successfully retrieved my s-pen from tmy Samsung S23 Ultra. To minimize the impact, I placed a towel on the table and tapped my phone on it. This helped dislodge the pen. I then tapped the phone again to remove any remaining sand or debris. The spring on the pen was stuck, so I gently tapped the pen until it clicked again. Now, the s-pen is fully functional. I hope this information proves helpful to someone in the future.