The interface includes various submenus which makes it very hard to use

Lakka does not support Dualboot, so you can't install another OS side-by-side.

There is no option to install the system in dual-boot with another OS on one hard disk drive.

A multi-emulator needs to make compromises.

It needs to be done over the CLI.

You need some knowledge if you want to add a different rom (lakka, like retroarch, supports only no-intro naming, there's no generic scan like emulationstation).