GUIDExporter.cs

using System.Linq;
using UnityEditor;
using UnityEngine;

public static class GUIDExporter
{
    [MenuItem( "Tools/Export GUID" )]
    private static void Export()
    {
        var list = AssetDatabase.GetAllAssetPaths()
            .Select( c => new { Path = c, Guid = AssetDatabase.AssetPathToGUID( c ) } )
            .OrderBy( c => c.Path )
            .Select( c => $"{c.Path},{c.Guid}" )
            .ToArray()
            ;

        var result = string.Join( "\n", list );

        Debug.Log( result );

        EditorGUIUtility.systemCopyBuffer = result;
    }
}