Open terminal that "adb" command available.

TerminalExtensions.cs

using System.Diagnostics;
using System.IO;
using UnityEditor;

public static class TerminalExtensions
{
    [MenuItem("Window/Run Terminal (at android sdk path) %t")]
    private static void RunTerminalAtAdbAvailableDir()
    {
        var adbDir = Path.Combine(UnityEditor.Android.AndroidExternalToolsSettings.sdkRootPath, "platform-tools");

        Process p = new Process();
        p.StartInfo.FileName = System.Environment.GetEnvironmentVariable("ComSpec");
        p.StartInfo.Arguments = $"/k cd /d {adbDir}";
        p.Start();
    }
}