Thanks for the feedback.
I tried forcing rotation by editing the config.txt and cmdline.txt files:
cmdline.txt: add "video=DSI-2:720x1280@60,rotate=90"
config.txt: add "dtoverlay=vc4-kms-dsi-ili9881-7inch"
These changes work fine under RPIos Lite, but Kodi still doesn't respond.
Apparently rotation via overlay was added in Kernel 6.6.63, I will test other parameters...