Set-BluetoothStatus.ps1

Param (
    [string]$BluetoothStatus
)

Add-Type -TypeDefinition @'
using System;
using System.Runtime.InteropServices;

public class MediaHelper
{
    public static bool IsPlayingSound()
    {
        IMMDeviceEnumerator enumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
        IMMDevice speakers = enumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia);
        IAudioMeterInformation meter = (IAudioMeterInformation)speakers.Activate(typeof(IAudioMeterInformation).GUID, 0, IntPtr.Zero);
        float value = meter.GetPeakValue();
        return value > 1E-08;
    }

    [ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")]
    private class MMDeviceEnumerator
    {
    }

    private enum EDataFlow
    {
        eRender,
        eCapture,
        eAll,
    }

    private enum ERole
    {
        eConsole,
        eMultimedia,
        eCommunications,
    }

    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("A95664D2-9614-4F35-A746-DE8DB63617E6")]
    private interface IMMDeviceEnumerator
    {
        void NotNeeded();
        IMMDevice GetDefaultAudioEndpoint(EDataFlow dataFlow, ERole role);
        // the rest is not defined/needed
    }

    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("D666063F-1587-4E43-81F1-B948E807363F")]
    private interface IMMDevice
    {
        [return: MarshalAs(UnmanagedType.IUnknown)]
        object Activate([MarshalAs(UnmanagedType.LPStruct)] Guid iid, int dwClsCtx, IntPtr pActivationParams);
        // the rest is not defined/needed
    }

    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("C02216F6-8C67-4B5B-9D00-D008E73E0064")]
    private interface IAudioMeterInformation
    {
        float GetPeakValue();
        // the rest is not defined/needed
    }
}
'@

if ([MediaHelper]::IsPlayingSound()) { return; }

If ((Get-Service bthserv).Status -eq 'Stopped') { Start-Service bthserv }
Add-Type -AssemblyName System.Runtime.WindowsRuntime
$asTaskGeneric = ([System.WindowsRuntimeSystemExtensions].GetMethods() | ? { $_.Name -eq 'AsTask' -and $_.GetParameters().Count -eq 1 -and $_.GetParameters()[0].ParameterType.Name -eq 'IAsyncOperation`1' })[0]
Function Await($WinRtTask, $ResultType) {
    $asTask = $asTaskGeneric.MakeGenericMethod($ResultType)
    $netTask = $asTask.Invoke($null, @($WinRtTask))
    $netTask.Wait(-1) | Out-Null
    $netTask.Result
}

[Windows.Devices.Radios.Radio,Windows.System.Devices,ContentType=WindowsRuntime] | Out-Null
[Windows.Devices.Radios.RadioAccessStatus,Windows.System.Devices,ContentType=WindowsRuntime] | Out-Null
Await ([Windows.Devices.Radios.Radio]::RequestAccessAsync()) ([Windows.Devices.Radios.RadioAccessStatus]) | Out-Null
$radios = Await ([Windows.Devices.Radios.Radio]::GetRadiosAsync()) ([System.Collections.Generic.IReadOnlyList[Windows.Devices.Radios.Radio]])
$bluetooth = $radios | ? { $_.Kind -eq 'Bluetooth' }
[Windows.Devices.Radios.RadioState,Windows.System.Devices,ContentType=WindowsRuntime] | Out-Null
Await ($bluetooth.SetStateAsync($BluetoothStatus)) ([Windows.Devices.Radios.RadioAccessStatus]) | Out-Null