Looks like an overnight airside stay will happen (or the trip will be postponed altogether) - unless restrictions are lifted in the coming days for additional countries.

It seems hard to enforce the 6 days rule on exit, plus I do not think there are any legal ground to enforce a fine or anything like this: if you “intended” to stay for 6 days but had to leaver earlier, I don’t think you’ll run into any issue, hence your suggestion might make sense. I found the police hotline to be easily available, and in English, very helpful if you have any doubt (you can always ask them “what’s the risk?”)