Most roads in Norway are open year round, but some scenic roads and mountai passes are closed.

The route you describe is about 30 hours driving total, that is a lot for 6 days. Gothenburg - Oslo is only 4 hours, but the other days are much longer. I guess you would want to stop and experience the places also? What do you want to do on this or the future trip?

There's a ferry between Strömstad and Sandfjord, but it would not really save much time. You might bring the car om the Hurtigruten ferry between Bergen and Ålesund, leaving Bergen in the evening and arriving Ålesund the next morning. Or leaving Ålesund at night and arriving in Bergen the next day.

Dropping Bergen (driving from Aurland to Ålesund) will spare some hours. Dropping Ålesund (drive from Stryn to Lom, then Oslo) would also spare some hours.