The T12 has OpenTX, mine does anyway. Came with V2.2.2
The T12 is physically smaller than the T16, plus you have to pay extra for Hall Effect gimbals on the T12, by buying the + which comes in Batman Black vs Toaster Cream. I have larger hands, I can fly fine in the T12, it just feels small. Works superbly.
The T12 or T16 will bind with much cheaper toy quads too, it doesn’t bind with the Eachine 010 or 013 out the box anymore, since the main board has changed in those, but it does bind with Hubsan, Flysky and some others, so you don’t need to buy an expensive FPV drone, spend the money on a better TX.
I got a second hand Eachine QX90 for $7 equivalent and it bound great with the T12, all I had to buy was batteries and props, which was another $15 total.