I think I remember Picochess uses the X desktop to support Mame chess engines.
I rarely use these and prefer the Wayland desktop, because it is smoother and doesn't have the display inconsistencies (e.g. width of dropdown menu, speed of opening the editor) I see with X.
However, autostart (/etc/xdg/lxsession/rpd-x/) will no longer boot to Picochess in Trixie if the Wayland desktop is used.
I was able to solve this issue by making the following changes:
Create a file in the folder: /home/pi/.config/labwc named: autostart
In the autostart file add this line.
/home/pi/kisosk.sh