What are their innards like? This looks very useful!

Since the inside dimensions and mounting rails are standard, there's lots of different compatible inserts you can get.

I cheapened out a bit at that point and went with double-height plastic drawers:

https://mero.ng/i/RixswvHW.jpg

Drawers generally come in single/double and plastic or aviation-grade welded alu.

There's also a bunch of funky stuff like cages to keep hot bread in for serving, and an after-market of "galley trolleys as designer furniture" companies that turn them into minibars with wine chillers and bottle storage and what not.