Sodium-ion batteries have started to appear in cars and home storage

I hope it's on the way, but I don't think the Pioneer Na is yet a sign of this revolution. This detailed review didn't leave me in a hurry to go get one, anyway:

https://www.youtube.com/watch?v=OoZ_g_MShTw

The idea with really cheap batteries is that they don't need good energy density. You just swap them every so often and put the one you aren't using in the charging rack. You could even carry your own reserve energy with you!

We used to have swappable batteries in virtually all of portable electronics. You could even get them in a rechargeable accumulator format. Virtually all of portable electronics has integrated batteries.

Yeah but AAs suck, and the newer more advanced batteries all have different voltages and require different charge circuitries so it’s hard to create a new standard for them.

It’s all depends on device size and required capacity. AA is not a bad choice for many cases. And there are other replaceable batteries with higher capacity e.g. 18650.

Most modern devices have an integrated 3.7v Lithium battery so standardisation should be possible but I see no market forces for this - devices with short lifespan (limited by a non-replaceable battery) are more profitable.