Is transport the bit that reels the tapes? I watched a YouTube video recently about these that said that it seems all these modern ones are using basically the same mechanism from a PRC factory, and thus the minimum size is quite large.

Since Sony doesn't manufacture their phenomenally small mechanisms anymore, the era of the tape sized tape player is gone unless someone invests millions in r&d and setting up manufacturing.

Also in terms of quality: fine, but the video found better quality from vintage units he had cleaned up.

I don't have the video saved sorry.