Hi, I’m afraid the end of the log you show doesn’t tell me very much (beyond the fact that it isn’t working before the first log entry).
But one problem you are likely to be having is that mir-kiosk currently doesn’t work on Classic without working around some problems described here: Can a confined Wayland server snap work on Classic systems? (And also Core systems?)
You’re probably not interested in that discussion, so just remove and reinstall mir-kiosk using:
sudo snap remove mir-kiosk
sudo snap install --devmode mir-kiosk
There can also be problems running graphics on Ubuntu Core in VMs. There’s a snap for that: ubuntu-core-vm
That is described here: https://community.ubuntu.com/t/snaps-to-develop-a-web-kiosk-on-ubuntu-core-using-wayland/6424