Hello Chris André Stranden,

> Are there any statements in the Palicanon that clearly states that it is
> possible to reach Nibbana without having such a strong samadhi that you can
> enter the jhana-states?

No. Otherwise there won't be so much arguments on this subject.

Let me point out the shortcomings of such sort of question.
It sounds like: "Can one become rich without work?".

The more useful question would mention exact means:
"Can one become rich by sleeping and watching TV?"
"Can one become rich by marriage?"
"Can one become rich by inheritance?"
or whatever means are implied.

The person who first wrote about practice without jhana,
"suddhavipassana", Ven. Buddhaghosa, writes in Atthakatha that the way
without jhanas is much harder, as crossing a river without a boat. The
practice with jhanas is like crossing a river ona boat. So Ven.
Buddhaghosa was not a proponent of "dry insight".

Best regards, Dmytro