Unity - simple 2D patrol component, upgraded from Unity Playground with gizmos and new functionality, follows Open/Closed principle, uses NaughtyAttributes for reorderable list of waypoints (remove line 4 and line 28 if unwanted)

Patrol2D.cs

using System;
using System.Collections.Generic;
using UnityEngine;
using NaughtyAttributes;

[RequireComponent(typeof(Rigidbody2D))]
public class Patrol2D : MonoBehaviour
{
    public enum FacingType
    {
        DontChange,
        Snap,
        Smooth
    }

    public bool isPatrolling = true;

    [Header("Movement")]
    public float speed = 5f;

    [Header("Orientation")]
    public FacingType facingType = FacingType.DontChange;
    public float smoothFaceSpeed = 7f;
    public Directions lookAxis = Directions.Right;

    [Header("Stops")]

    [ReorderableList]
    public List<Vector2> waypoints;

    public bool waitAtEachStop = false;
    public float waitTime = 1f;
    protected float currentWaitTime = 0f;
    protected bool isWaiting = false;

    [Header("Preview")]
    public bool previewWaypoints = true;
    public float gizmoScale = 0.3f;

    public static event Action<GameObject> OnReachedWaypoint = delegate { };

    protected new Rigidbody2D rigidbody2D;
    protected Vector2[] newWaypoints;
    protected int currentTargetIndex;

    protected virtual void Awake()
    {
        rigidbody2D = GetComponent<Rigidbody2D>();
    }

    protected virtual void Start()
    {
        if(isPatrolling) InitializePatrol();
    }

    protected virtual void InitializePatrol()
    {
        currentTargetIndex = 0;

        newWaypoints = new Vector2[waypoints.Count + 1];
        int w = 0;
        for (int i = 0; i < waypoints.Count; i++)
        {
            newWaypoints[i] = waypoints[i];
            w = i;
        }

        //Add the starting position at the end, only if there is at least another point in the queue - otherwise it's on index 0
        int v = (newWaypoints.Length > 1) ? w + 1 : 0;
        newWaypoints[v] = transform.position;

        if (facingType== FacingType.Snap || facingType == FacingType.Smooth)
        {
            SetAxisTowards(lookAxis, transform, ((Vector3)newWaypoints[1] - transform.position).normalized);
        }
    }

    protected virtual void Update()
    {
        if (isPatrolling && waitAtEachStop && currentWaitTime > 0f)
        {
            currentWaitTime -= Time.deltaTime;
            isWaiting = true;
            return;
        }
        else
        {
            isWaiting = false;
        }
    }

    public virtual void FixedUpdate()
    {
        if (!isPatrolling) return;

        Vector2 currentTarget = newWaypoints[currentTargetIndex];
        Vector2 currentDirection;

        // Snap Rotate
        if (facingType == FacingType.Snap && facingType != FacingType.Smooth)
        {
            currentDirection = UpdateDirection(currentTarget);
            SetAxisTowards(lookAxis, transform, currentDirection);
        }

        // Smooth Rotate
        if (facingType == FacingType.Smooth)
        {
            currentDirection = UpdateDirection(currentTarget);
            float angle = Mathf.Atan2(currentDirection.y, currentDirection.x) * Mathf.Rad2Deg;
            transform.rotation = Quaternion.Lerp(transform.rotation, Quaternion.AngleAxis(angle, Vector3.forward), Time.deltaTime * smoothFaceSpeed);
        }

        if (isWaiting) return;

        // Move toward waypoint
        rigidbody2D.MovePosition(transform.position + ((Vector3)currentTarget - transform.position).normalized * speed * Time.fixedDeltaTime);

        if (Vector2.Distance(transform.position, currentTarget) <= .05f)
        {
            rigidbody2D.MovePosition((Vector3)currentTarget);

            //new waypoint has been reached
            OnReachedWaypoint.Invoke(gameObject);
            if(waitAtEachStop) currentWaitTime = waitTime;
            currentTargetIndex = (currentTargetIndex < newWaypoints.Length - 1) ? currentTargetIndex + 1 : 0;
        }
    }

    protected virtual Vector2 UpdateDirection(Vector2 currentTarget)
    {
        return ((Vector3)currentTarget - transform.position).normalized;
    }

    public virtual void Reset()
    {
        waypoints.Clear();
        Vector2 thisPosition = transform.position;
        waypoints[0] = new Vector2(2f, .5f) + thisPosition;
    }

    protected void SetAxisTowards(Directions axis, Transform t, Vector2 direction)
    {
        switch (axis)
        {
            case Directions.Up:
                t.up = direction;
                break;
            case Directions.Down:
                t.up = -direction;
                break;
            case Directions.Right:
                t.right = direction;
                break;
            case Directions.Left:
                t.right = -direction;
                break;
        }
    }

    public enum Directions
    {
        Up,
        Right,
        Down,
        Left,
    }

    protected virtual void OnDrawGizmosSelected()
    {
        if (!previewWaypoints) return;

        for (int i = 0; i < waypoints.Count; i++)
        {
            Gizmos.color = Color.yellow;
            Gizmos.DrawSphere(new Vector3(waypoints[i].x, waypoints[i].y, transform.position.z), gizmoScale);

            Gizmos.color = Color.green;
            if (i == 0)
            {
                Gizmos.DrawLine(waypoints[i], transform.position);
            }
            else
            {
                Gizmos.DrawLine(waypoints[i], waypoints[i-1]);
            }
        }
    }

    [ContextMenu("Start Patrolling")]
    public virtual void StartPatrolling()
    {
        isPatrolling = true;
        InitializePatrol();
    }

    [ContextMenu("Stop Patrolling")]
    public virtual void StopPatrolling()
    {
        isPatrolling = false;
    }
}