Trying to make Sygic to use car stereo

Hello to all!

I purchased the full version of SoubdAbout yesterday.
I have a Galaxy Note 2, a Samsung Galaxy Tab 3 (the 8", WiFi only) and the car stereo is a Pioneer MVH-X370BT.
I am not interested in listening to music coming from the phone or the tablet.

The phone is on Android 4.4.2 and the tablet is on Android 4.4.4, if that is of any help.
The phone works fine (via bluetooth) with the car stereo when receiving / making calls.

What I am trying to achieve is to get Sygic (which is installed in both the phone and the tablet) to interrupt music or radio so that I can hear the program's instructions (turn left, turn right etc.) from the car's speakers. I fiddled with all the settings that made sense for two hours, but I couldn't manage to make it work. I restarted both devices several times after I installed SoundAbout, I unpaired and re-paired both devices, I tried using only one device at a time (in case the car stereo could not handle both devices simultaneously), nothing. I simply could not get any of the two devices to interrupt the audio and send satnav instructions to the car stereo. The instructions were heard by the device only. Please note that I tried the Sygic setting under [Sound and Notification > Advanced > Phone Speaker] both on and off.

The main thing is to get the tablet working, as the phone is rarely used as a satnav.
Still, it would be nice to get the phone working too if that is at all possible.
Ideally, I'd like to have the tablet send satnav instructions and the phone send calls to the car's stereo, both interrupting the music played by the flash drive or radio when necessary.

Could you please guide me as to what settings I should use?

Thanks in advance and please accept my apologies for the lengthy post.

Anyone?

It depends on the Navigation app and how it utilizes Text To Speech. Right now, Google Maps(latest release) doesn't seem to use the selected TTS engine selected in Android. I don't know if they have done that on purpose.

I haven't looked at Sygic for a while, but there are some threads regarding Navigation app audio using Bluetooth phone profile:

https://soundabout.forumotion.com/t418-using-google-navigation-waze-or-co-pilot-and-even-ivona-for-the-voices

https://soundabout.forumotion.com/t202-navigation-text-to-speech-audio-to-various-outputs-bluetooth-mono-in-car