Hey,
I have two other sets on itch.io in isometric fashion : https://nulllgames.itch.io/isometric-military-vehicles and https://nulllgames.itch.io/isometric-spaceship-sprites
The Indoor set has 2928 image files. I don't have a file handy that shows a full index, but I've made a screenshot of the entire folder : http://nulll.net/assets/previews/
Anything in particular you wish to know more details about?
I have several sets in the works as well : an outdoors set with the same dimensions and style as the Medieval indoor tiles and a set of fantasy characters (knights, wizards, etc) also matching the indoor and outdoor tiles.
I'm also working on contemporary city sets with houses, cars, street tiles, etc, but no ETA on any of these sets.
I've done custom work before, here's an image of a set for a war-themed game : 