There might be some misunderstanding, the SiriusXM Satellite Radio Receiver Home Kit Model #SXDH4 is a home dock with antenna and power adapter but it does not come with a Satellite radio. This is a spare home dock so you can bring your Satellite radio from your car or office to your home for example. The SXDH4 is compatible with the SXABB1 in that you could plug a 3.5mm(1/8in) stereo cable from the home dock to the SXABB1 and use the SXABB1 as an amplifier and speakers for the SXDH3. But still a satellite radio is required that is sold separately,

Yes, the TTR3 Wi-Fi Sound Station has a built in Wi-Fi antenna.

No, the T1808 is a SAT Ready head unit so it requires a much older obsolete satellite tuner. However, the T1808 has an Aux input so your Scion may have a 3.5mm (1/8in) Aux in socket somewhere on your dash or in the glove box. If your vehicle has this Aux input then you can use a Satellite radio such as Roady BT or Onyx EZR which support Aux output as an alternate solution.

If your vehicle originally had a Satellite radio then your vehicle would have a Satellite antenna which you could connect to the Roady BT instead of using the NGVA3 Satellite antenna that comes with the Roady BT. However, the NGVA3 antenna has much better interference protection and therefore will provide better reception compared to the original equipment antennas included in many older vehicles. I wouldn't recommend you use your old Satellite antenna but you can try it and drive around your routine commutes and other routes you frequent and see if the performance is acceptable. If you find you are having a lot of mutes that do NOT correlate with trees, buildings or mountains that are blocking the view to the south which will cause mutes that are unavoidable, then you should switch to the NGVA3 and compare the reception. The NGVA3 can be challenging to dress the antenna cable to get a clean installation so I can see why you might want to use the factory Satellite antenna so it may be worth a try.