I will not be defeated by technological incompatibility. I have an iPod Nano 7 with Bluetooth 4.0 and a 3.5mm headphone jack. I have a Soundcore Boom 2 Plus portable high-power stereo speaker with Bluetooth 5.3 and 3.5mm audio input jack.
I want to play music from the iPod to the speaker but the two Bluetooth versions aren't communicating properly. I can pair the iPod and the speaker but the volume level remains at zero regardless of how I fiddle both devices' volume controls.
Next I tried running a 3.5mm stereo cable between the iPod and the speaker but the iPod's jack is set up in such a way that I can't get the plug on the cable all the way into the iPod, so anything that does play is in mono.
However, there's another item in my collection that saves the day, a 12South AirFly Pro Bluetooth audio transmitter/receiver that has a 3.5mm stereo plug at one end. I set that into Receive mode and pair it with the iPod. Then plug the AirFly device into the aux in jack on the speaker.
This works perfectly well, now I have a viable wireless audio connection between the speaker and the iPod.
But while the speaker has a battery life of 20 hours continuous use at 50% volume with bass boost off, the AirFly has only 16 hours. But the speaker has a two-way USB-C power connection. It can be used to charge the speaker's battery or to charge other devices like iPods or iPhons or even AirFly Pro thingies.