I actually am using an Anker SoundCore too! I connected it to the Pi 4b as a Bluetooth device, and then I had to select it as the audio device from the sound menu. If I was doing this headless, I'm not sure that I could do it... but via the Desktop, it was pretty easy.
For pros, it has a lot less static than it does with an audio cable connected to the Pi. The sound is very clear. For cons, it doesn't always connect when I reboot. I haven't tinkered with it to see if I can make it work all of the time, because the battery usually runs out because I forget to charge it again. But if you want me to try and try some things to help you test, let me know!
Kyle