Have you seen any suitable case or enclosure to stick one of this inside to protect it?

On the ZYPDS board there are two sets of solder pads, not just what you circled in yellow, but also the two pads to the left of that yellow circle. Bridging both sets results in a voltage of 5v. Bridging the right-most set results in a voltage of 12v. I can de-solder and test the results of just the left-most set of pads but I imagine it will output 9v in that configuration.

The ZY12PDG (so called "industrial grade") appears to be functionally identical to the ZY12PDN only with less components (terminals, buttons etc.)
It may or may not come with the button installed (mine was with button, it sits at the white circle on the PCB)

VBUS = +
GND = -
CC1 and CC2 = every USB-C cable has only one CC-wire. Choose one, it doesn't matter which. (it simply determines the orientation of the USB-C plug which is obviously not present in this case)
Trig = short it to ground to emulate button press

The large solder pads on the back are plus and minus and are directly connected to VBUS and GND. Please note that is the input and output at the same time!

more observations:

• my yellow (9V) looks very green, very hard to discern from the actual green (15V)
• I soldered mine directly to the end of a 65W Thinkpad USB-C Power supply (blue=cc, silver=ground, red=VBUS+)
  it worked very well, however it doesn't support 12V
• oddly it will display the colors exactly in the same order and doesn't skip voltages that are not supported, so that for me first color is 5V=red, 9V=yellow, 15V=green, 20V=lightblue. However in programming mode the colors are accurate according to your info, so that darkblue actually results in 20V (I suspect the ZY12PDN would show the same behavoir)
  -another example: I program it to "light blue" - After the power cycle it correctly results in 15V, but it shows "green"

Therefore I conclude: in programming mode the light color accurately reflects the voltage level listed by you, but in "normal" mode the color is simply incremented for each supported voltage level which is depended on the power source used.
First Voltage = red, second voltage= yellow, etc.

Overall I am very happy with this, even if it took me some time to figure out how it works.

Does anyone know more about the current selection for those modules?

Suppose you have power supply that offers PD profiles from 5 to 20V at 2A each, and a trigger module capable of 5A.

Will a trigger module:

a) Attempt to negotiate 20V5A and fail -> 5V output
b) Negotiate 20V2A -> 20V
c) Something else?

Thanks!

I am trying out my USB pd board and I have seen a strange mode when after delivering 5 V for a while it goes to blue blinking mode. What could it be ?

I found one more interesting model " ZYPDCH", very similar to ZYPDS.

https://www.aliexpress.com/item/4001163626853.html

I haven't tested this, but apparently you can select all voltages with different solder bridge combinations.

I will save the key parts of the listing here in case it goes down:

Volume: length 21mm width 11mm thickness 4.3mm

Input protocol: PD2.0 or PD3.0
Trigger gear: 5V, 9V, 12V, 15V, 20V, see the figure below for the specific setting method
Static power consumption: less than 1.5mA in all gears
Output pads: 4 pitches of 2.54mm, square negative round positive
Method of setting voltage: As shown in the figure, the red dot represents two pad halves connected by a drop of solder.
The output is connected to 20V by default. It is recommended to actually check the output voltage before use.
If you set 15V, connect the four jumper pads on the front with 20V, and then connect the 15V jumper pads on the back.