Sorry, we haven’t verified kind of this dummy display port adapter.
For your use case, you might could refer to the following steps to enable virtual display for VNC.
Step 0: Enable Screen sharing through connecting monitor first
Settings → Sharing → Screen Sharing → set ‘Active’
Step 1: update and install xserver-xorg-video-dummy
$ sudo apt update
$ sudo apt install xserver-xorg-video-dummy
Step 2: Create config for dummy virtual display
$ cd /etc/X11
$ sudo vim xorg.conf.dummy
Step3: Add the following contents in xorg.conf.dummy (resolution 1920*1080 as example)
Section "Device"
Identifier "DummyDevice"
Driver "dummy"
VideoRam 256000
EndSection
Section "Screen"
Identifier "DummyScreen"
Device "DummyDevice"
Monitor "DummyMonitor"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1920x1080_60.0"
EndSubSection
EndSection
Section "Monitor"
Identifier "DummyMonitor"
HorizSync 30-70
VertRefresh 50-75
ModeLine "1920x1080" 148.50 1920 2448 2492 2640 1080 1084 1089 1125 +Hsync +Vsync
EndSection
Step 4: Update /etc/X11/xorg.conf
$ cp xorg.conf xorg.conf.backup
$ cp xorg.conf.dummy xorg.conf
Step 5: Reboot the board
$ sudo reboot