I wired a line level transmitter that sent a Bluetooth signal to a receiver that was connected to a subwoofer at one time. It was a lot of work... It was similar to what Broadway Limited is doing in HO and N currently.
If you go look at Bluerailtrains.com you will see their Bluetooth control system can use a speaker like the one you mention. So the answer would be yes, it can be done. But as John points out, is it really worth it? That's up to you.
I would love to see every piece of rolling stock equipped with a receiver and a speaker. The engine could act as a mixer and send different sounds to different cars. Perhaps even be programmable... Send engine sounds to the first 3 cars in the consist, fading from 1-3. Send flange squeal and clickety clack to cars 5, 10, and 15. Specific mechanical reefer sounds to cars 6 and 7. Stock car sounds to 12-14. And finally crew chatter to the caboose. You get the idea...
Of course just putting appropriate sounds into the cars like the Lionel PS-1s and Tank cars is also a good way to go and less complex, but you can't send the engine sounds to them obviously.
If you just want to add one speaker you can't beat a simple tether though. Just watch the impedance as John mentioned.