OpenBSD on GPD Win

Update March 2019

miniroot65.fs boots fine.
In console mode the orientation is now correct by default.
xorg.conf for rotating X is this:
Section "Monitor" Identifier "DSI-1" Option "Rotate" "right" EndSection

Setup - EFI bootable USB stick

Used vmd(8) to spin up a virtual machine and do a GPT install. The default MBR install won't work because the device uses EFI boot only.
OBSDROOT="/home/gpd" vm "openbsd" { disable memory 1024M boot $OBSDROOT/bsd.rd disk $OBSDROOT/install62.iso disk $OBSDROOT/2Gstick.fs owner gpd }
Write the virtual disk image to USB stick (sdX).
# dd if=2Gstick.fs of=/dev/rsdXc bs=1M

Booting the USB stick

Press ESC after power-on to change the boot order.

Diplay will switch orientation during boot from left-to-right to upside-down, once inteldrm(4) is loaded.

Back to left-to-right after startx(1).

Initial config

To save some time booting, disable library relinking. Also enable apmd(8) with automatic power management.
To save some more time booting, disable kernel relinking.
# mv /var/db/kernel.SHA256 /var/db/kernel.SHA256.disabled

X11 rotate

After some unsuccessful tinkering with getting the display orientation right with inteldrm(4) I switched to unaccelerated framebuffer display. See efifb(4) and wsfb(4). First disable inteldrm(8) driver in the kernel and reboot. Then the following xorg.conf(5) should work.
# echo "disable inteldrm\nquit" | config -ef /bsd
# reboot
Section "Device" Identifier "Framebuffer0" Driver "wsfb" Option "Rotate" "CW" EndSection

Not configured IDs

INT33A4   Intel(R) Power Engine Plug-in
INT33BD   Intel(R) Sideband Fabric Device
INT34D3   Intel(R) Power Management IC Device
INT33FE   Intel(R) Battery Management Device
INTL9C60   Intel(R) Serial IO DMA Controller
8086228A   Intel(R) Serial IO UART Controller
BCM2E7E   Broadcom Serial Bus Driver over UART Bus Enumerator
8086228E   Intel(R) Low Power Subsystem SPI Controller
10EC5645   Realtek I2S Audio Codec
GDIX1001   Goodix Touch HID
808622A8   Intel SST Audio
ACPI0011   ACPI generic button device
ACPI000C   ACPI-Compliant Virtual Power Controller
MSFT0101   Intel Trusted Platform for Windows
INT3400   Intel(R) Dynamic Platform and Thermal Framework Driver
INT3407   Intel(R) Dynamic Platform and Thermal Framework Power Participant
INT3403   Intel(R) Dynamic Platform and Thermal Framework Generic Participant Driver
INT3409   Intel(R) Dynamic Platform and Thermal Framework Ambient Participant Driver
INT3406   Intel(R) Dynamic Platform and Thermal Framework Display Participant Driver
USBC000   UCSI USB Connector Manager