Thanks for the information @TotallyInformation !!!
For the moment i think i will use the non-route solution. I am not so firm in javasript that I could implement my own subrouter.
But I don't think multiple router instances are necessarily needed for nested routing. Nested routing can also be solved using an instance by specifying the sub-routes within the main routes.
Starting from such a configuration:
const routerConfig = {
    routeContainer: '#routecontainer',
    routes: [
        {
            id: 'lights', src: './routes/lights.html',  type: 'url',
            title: 'Lights'
            subrouteContainer: '#lights-container' 
            subroutes: [
                {
                    id: 'lights/kitchen',
                    src: './routes/lights-kitchen.html',
                    type: 'url',
                    title: 'Kitchen',
                },
                { ... }
        }, 
    ],
};
Of course, it is then necessary to adapt the router logic accordingly and possibly the handling of the navigation events, or am I seeing this wrong?