My car came with the sideways facing kinder seat. Not ideal in modern conditions
I have looked at options and the best advice seems to be to take the kinder seat out and replace it with the parcel shelf. When doing that, secure mounting points for a child seat underneath the shelf so that the seat is in the middle of the car. Seat must have integral seat belt harness. Kids legs sit atop the transmission tunnel
I have not done this, although have seen a similar set up and it looked OK.
I know there are concerns about roll-over protection.