Enabling Fake KMS on Pi 4 breaks screen rotation. Any workaround for EGLFS apps on non-desktop setups?

[Diracsbracket]

Hi.
After finally cross building Qt 5.15.1 for my Pi 4 and building and installing some app, I got the infamous Could not find DRM device! error.

So, as suggested by @sierdzio in this post, I enabled the Fake KMS driver using raspi-config.

Enabling this is known to break the display rotation setting in /boot/config.txt. With desktop installations, it seems this can be resolved using the xrandr utility.

Are there any workarounds for EGLFS applications on non-desktop installations?

Edit:
A reply to my post on the Raspberry forum made me aware of the video= settings that you can add to cmdline.txt as must apparently be done for KMS and Fake KMS video driver modes.

So, I tried adding

video=HDMI-A-1:1080x1920M@60,margin_left=0,margin_right=0,margin_top=0,margin_bottom=0,rotate=90

but that had no effect.