Moves the Content transform so the current selected object will be inside the Viewport rect

ScrollToSelectionBehaviour.cs

// Source: https://gist.github.com/Z4urce/e1719b3c1641537ced54da24d911f0b0
// Moves the Content transform so the current selected object will be inside the Viewport rect

using UnityEngine;
using UnityEngine.EventSystems;

namespace Utils
{
    public sealed class ScrollToSelectionBehaviour : MonoBehaviour
    {
        public RectTransform Viewport;
        public RectTransform Content;

        public bool Horizontal = true;
        public bool Vertical = true;
        public float DistanceDeltaQuotient = 1000f;

        public void Update()
        {
            var selected = EventSystem.current.currentSelectedGameObject;
            if (selected == null || !selected.TryGetComponent<RectTransform>(out var rectTransform)) {
                return;
            }

            SnapToTarget(rectTransform);
        }

        private void SnapToTarget(RectTransform rectTransform)
        {
            Vector2? snapPos = GetTargetRectSnapPos(rectTransform);
            if (!snapPos.HasValue) {
                return;
            }
            
            var anchoredPos = Content.anchoredPosition;
            var destination = new Vector2(Horizontal ? snapPos.Value.x : anchoredPos.x, Vertical ? snapPos.Value.y : anchoredPos.y);
            float maxDistanceDelta = Time.deltaTime * DistanceDeltaQuotient;

            Content.anchoredPosition = Vector2.MoveTowards(anchoredPos, destination, maxDistanceDelta);
        }

        private Vector2? GetTargetRectSnapPos(RectTransform targetRectTransform)
        {
            Canvas.ForceUpdateCanvases();
            
            var rectMinWorldPos = (Vector2) targetRectTransform.TransformPoint(targetRectTransform.rect.min);
            var rectMaxWorldPos = (Vector2) targetRectTransform.TransformPoint(targetRectTransform.rect.max);

            Vector2? minSnap = CalculateViewportTargetDist(rectMinWorldPos);
            Vector2? maxSnap = CalculateViewportTargetDist(rectMaxWorldPos);

            return maxSnap ?? minSnap;
        }
        
        private Vector2? CalculateViewportTargetDist(Vector2 globalPos)
        {
            var invTransTarget = (Vector2) Viewport.InverseTransformPoint(globalPos);
            if (Viewport.rect.Contains(invTransTarget)) {
                return null;
            };

            var invTransContent = (Vector2) Viewport.InverseTransformPoint(Content.position);
            return invTransContent - invTransTarget;
        }
    }
}