I have got a workaround on this by luck. But I'm not familiar with the dependencies here. I guess lightdm/unity-greeter has a default but also respect individual user's settings. so I created /var/lib/AccountsService/users/admin (the admin account set during installation).
[InputSource0]
xkb=us
[InputSource1]
xkb=jp
[InputSource2]
xkb=se
Then restart lightdm or reboot will show the keyboard selection
I have got a workaround on this by luck. But I'm not familiar with the dependencies here. I guess lightdm/ unity-greeter has a default but also respect individual user's settings. so I created /var/lib/ AccountsService /users/ admin (the admin account set during installation).
[InputSource0]
xkb=us
[InputSource1]
xkb=jp
[InputSource2]
xkb=se
Then restart lightdm or reboot will show the keyboard selection