I recently picked up a T Gauge starter set that includes a small passenger train, track, power supply, and cleaning accessories. The video below shows my first look at the set as well as the scale in general. Besides the fact that trains this small can even work, I was most surprised about how well the trains stay on the rails. The trains have magnets inside them and the rails are apparently steel or some type of iron-based alloy. The net result is that you can tip the track at crazy angles or even shake the entire baseboard that the track is on quite violently and the train will keep on going around the track without falling off. It is also not as hard as you might think to get the train on the tracks properly without the retailer as the magnets help with aligning the wheels properly. I also found the track more realistic than what I was expecting. The rails are of course very oversized for the scale, but scale height rails would be impractical at this size.
You can see in the image below everything you get with the starter set. The entire box is very small.
I picked up the starter set here: https://www.vcshobbies.com/product-category/t-gauge-model-trains/starter-sets/
I'm currently working on building a T Gauge train layout on a hat that I can wear around to train shows and things like that. I'll hopefully have that project done within a couple of weeks, so look for that video soon.
Here is the full video on my first look at T Gauge: