It might be:
/usr/lib/systemd/system/connman.service.d/01-require-home-mount-to-be-present.conf
that prevents ConnMan from starting as it is set to wait for the home mount. Do you have access to the device and to get output from systemd: systemctl status connman. And if that file is removed/relocated, does it change after systemctl daemon-reload && systemctl start connman ?
EDIT: you may need to also change the /etc/connman/main.conf a bit:
# Comment out these lines
#StorageRoot = /home/.system/var/lib
#UserStorage = .local/share/system/privileged
# Set this to false (or just comment out)
EnableLoginManager = false
which will return to using ConnMan in a single, root user mode with the last change. The locations for files are then /var/lib/connman after the storage dir’s return to default.