Solved (I hope, worked after rebooting after failing twice) by following the suggestion in http://community.frame.work/t/solved-ubuntu-23-04-doesnt-recognize-touchpad-properly/ to blacklist the ps2 mouse
echo "blacklist psmouse" | sudo tee -a /etc/modprobe.d/blacklist.conf
Strangely enough it did work in the live ‘cd’ (usb) from which I installed.