They mentioned the 'T' scale which I recently came across.
https://www.youtube.com/watch?v=PNje4KTLZT4
It is 1:450 scale and half the size of the Z scale.
When describing starter sets, the track area is dimensioned in mm. https://www.tgauge.us/product/452/20/lner-125-hst-train-set
> The 120mm loop included in this starter set will cover an area of 253mm x 372mm (10" x 14 3/4").