Trying to combine my inventory and weapon system

So I watched some tutorials and made a inventory and weapon system but the problem is these system were both taken from different kind of videos. So I want to combine both of them.

this is my weapon switch system

    using UnityEngine;
    
    public class Weapon_switching : MonoBehaviour
    {
        public int selectedWeapon = 0;
    
        // Start is called before the first frame update
        void Start()
        {
            SelectWeapon();
        }
    
        // Update is called once per frame
        void Update()
        {
            int previousSelectedWeapon = selectedWeapon;
    
            if (Input.GetAxis("Mouse ScrollWheel") > 0f)
            {
                if (selectedWeapon >= transform.childCount - 1)
                    selectedWeapon = 0;
                else
                selectedWeapon++;
            }
            if (Input.GetAxis("Mouse ScrollWheel") < 0f)
            {
                if (selectedWeapon <= 0)
                    selectedWeapon = transform.childCount - 1;
                else
                    selectedWeapon--;
            }
    
            if(Input.GetKeyDown(KeyCode.Alpha1))
            {
                selectedWeapon = 0;
            }
        
            if (Input.GetKeyDown(KeyCode.Alpha2) && transform.childCount >= 2)
            {
                selectedWeapon = 1;
            }
    
            if (Input.GetKeyDown(KeyCode.Alpha3) && transform.childCount >= 3)
            {
                selectedWeapon = 2;
            }
    
            if (Input.GetKeyDown(KeyCode.Alpha2) && transform.childCount >= 4)
            {
                selectedWeapon = 3;
            }
    
            if (Input.GetKeyDown(KeyCode.Alpha2) && transform.childCount >= 5)
            {
                selectedWeapon = 4;
            }
    
            if (previousSelectedWeapon != selectedWeapon)
            {
                SelectWeapon();
            }
        }
    
        void SelectWeapon ()
        {
            int i = 0;
            foreach (Transform weapon in transform)
            {
                if (i == selectedWeapon)
                    weapon.gameObject.SetActive(true);
                else
                    weapon.gameObject.SetActive(false);
                i++;
            }
        }
    }

this is the equipment code

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    
    [CreateAssetMenu(fileName = "New Equipment", menuName = "Inventory/Equipment")]
    public class Equipment : Item
    {
        public EquipmentSlot equipSlot;
    
        public int armorModifier;
    
        public override void Use()
        {
            base.Use();
            EquipmentManager.instance.Equip(this);
            RemoveFromInventory();
        }
    }
    
    public enum EquipmentSlot { Armor, Smg, Pistol, Rifle, Heavy}

this is the equipment manager

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;
    
    public class EquipmentManager : MonoBehaviour
    {
        #region Singleton
        public static EquipmentManager instance;
    
        private void Awake()
        {
            instance = this;
        }
    
        #endregion
    
        Equipment[] currentEquipment;
    
        public delegate void OnEquipmentChanged(Equipment newItem, Equipment oldItem);
        public OnEquipmentChanged onEquipmentChanged;
    
        Inventory inventory;
    
        private void Start()
        {
            inventory = Inventory.instance;
    
            int numSlots = System.Enum.GetNames(typeof(EquipmentSlot)).Length;
            currentEquipment = new Equipment[numSlots];
        }
        public void Equip (Equipment newItem)
        {
            int slotIndex = (int)newItem.equipSlot;
    
            Equipment oldItem = null;
    
            if (currentEquipment[slotIndex] != null)
            {
                oldItem = currentEquipment[slotIndex];
                inventory.Add(oldItem);
            }
    
            if (onEquipmentChanged != null)
            {
                onEquipmentChanged.Invoke(newItem, oldItem);
            }
    
            currentEquipment[slotIndex] = newItem;
        }
    
    }

I wanna make it so when I press 1 on the keyboard it will equip the smg and pistol when I press 2 and be switchable with the mouse scrollwheel too
I am new at the game making stuff and still trying to learn and I would be very happy if someone could help me.
edit: forgot to say, I want to abandon the old method and switch between my weapons using the equipment system

You might be better off just choosing which of the above works better for you (Weapon or Equipment), then just deleting the other one while putting all of its features into the first one.

You need to identify what each one does for you that is different first though, obviously.

Be sure to separate user intentions (what the user clicks or presses) from the meaning (select next weapon) from the processing of that intent (actually changing the internal data representing what weapon is active).

Thanks for the advice