Main.cs

using UnityEngine;
using UnityEngine.UI;

public class Main : Button {
    void OnGUI() {
        // Q: Enter PointerLock state
        if (Input.GetKeyDown(KeyCode.Q)) {
            EnterPointerLock();
        }
        
        // O: Exit PointerLock state 
        // When entered with CLICK: Releases Pointer Lock but does not Reveal Cursor.
        // When entered with Q: Works as intended. Released Pointer Lock and Reveals the Cursor.
        if (Input.GetKeyDown(KeyCode.O)) {
            ExitPointerLock();
        }
                
        // ESC: Exit PointerLock state
        // When entered with CLICK: Releases Pointer Lock but does not Reveal Cursor.
        // When entered with Q: On FIRST press it Releases Pointer Lock (cursor still hidden), on SECOND press it Reveals the Cursor!
        if (Input.GetKeyDown(KeyCode.Escape)) {
            ExitPointerLock();
        }
    }
    
    void EnterPointerLock() {
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;       
    }
    
    void ExitPointerLock() {
        Cursor.lockState = CursorLockMode.None;
        Cursor.visible = true;      
    }

    public override void OnPointerDown(UnityEngine.EventSystems.PointerEventData eventData) {
        EnterPointerLock();
    }
}