I know, this may not be relevant for most of us, but I wanted to report it anyhow for the records.

I needed something from local Conrad store (in DEU) and in order to justify the trip to town I took a
"Touchscreen für Arduino Uno/Mega" from Tru Components to see if I can use it for Teensy.
After some search I found that it more or less identical to Vellemann VMA412 https://www.velleman.eu/products/view/?id=435582 with more information.
The short version:
Even if powered with 5 V (on standard Uno/Mega pins) it works internally with 3.3 V, so connecting to Teensy 3.6 was not a problem.
Using SW from https://github.com/vmalepati1/Teensy...rallel-Library I got it working but only with CPU speed of up to 48 MHz
Using standard Touchscreen was working too, whereby using rxplate =0 removed final issue with pressure readings

I'm not saying that this SW is perfect, but it is a good starting point and improvements are possible.

Finally, if you have a SPI version of the display, forget about what I said above.