What if stakeholders are not interested in the delivery of the increment?
I think, ideally, each increment of the product would be used in some way by stakeholders. Is it normal if the stakeholders only come in contact with the increment during the Sprint Review but it is not delivered to them because they have no interest in using it until the last sprints? Are there any tips to deal with this situation?
What if stakeholders are not interested in the delivery of the increment?
Do they understand the gamble? What if they wait until the time you describe, and then find out that in practice the value isn't there? You'd wonder if it might be best to have an interest in value earlier, when something can be done about it, and an early return obtained on the investment being made.
Looking at the product is better than not looking at the product. Looking at someone else use the product is better than just looking at the product. Using the product in a highly-controlled environment is better than looking at someone else use the product. Large numbers of key stakeholders using the product in a highly-controlled environment is better than a few key stakeholders using the product. Putting the product directly in the hands of end-users and getting real-world feedback is the best.
It seems like you are already above "not looking at the product", assuming that you have key stakeholders participating in the Sprint Review. Figuring out why they don't want to use the product at all until later would be a good start. Getting over those hurdles would be the next step, but you can't do that until you figure out why they are there in the first place.
When I get you, they want to have the "complete" product at the end. Do they give feedback during the review so you adapt the upcoming work? Did you ask what they are missing? - If they miss a major functionality, then it could be a matter of not ideal prioritization.
Also asking them for active feedback can "force" them to come out of their confort zone. Especially when you have longer release cycle, the awareness for early feedback has to be sharpened at the stakeholder.
Just a thought. Maybe you are not delivering the correct increments. If I was in the position that the stakeholders see the increment in Sprint Review but are not interested in what has been done, I would ask them if the team could have delivered something else that they would be interested in using. Get feedback from them on how you are organizing your increments.
Also, I have experienced many times where the specific increment that was created was not something that the stakeholders were interested in using. But that lead to a discussion of what is missing in order for them to be interested in using it. The next iteration was something that the stakeholders were interested in using.
In this situation, just like any other, empirically inspect and adapt.