There are too many variables for Android touch pressure to change the public API unless more people want it. A workaround to get touch pressure reliably on Android:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class NewBehaviourScript : MonoBehaviour
{
int m_TouchPressureSupported = -1;
public bool touchPressureSupported
{
get
{
if (m_TouchPressureSupported == -1)
{
var javaClass = new AndroidJavaClass("com.unity3d.player.Utilities");
m_TouchPressureSupported = javaClass.CallStatic<int>("isTouchPressureSupported");
}
if (m_TouchPressureSupported == -1)
throw new System.Exception("Failed to query touchPressureSupported");
return m_TouchPressureSupported == 1;
}
}
private void OnGUI()
{
GUILayout.Space(20);
GUILayout.Label($"TouchPressureSupported: {touchPressureSupported}");
}
}