All that is needed is an outboard digital audio decoder. Simple and
guaranteed safe option.

There is no guarantee that the speaker lines are at a safe voltage
level to try and tap and audio out.

Seems to me that this should have been a consideration when buying the
low end low feature model. In order for them to sell at these lowest
prices, something has to be cut, like analog audio out jacks, etc.
Manufactures really are not too concerned with making the new stuff
completely compatible with old obsolete equipment like the audio system
attempting to be used.