The biggest issue is what Motta thinks. Because if Motta is willing to work with him and sees a possibility of him being used regularly, then Chiesa should definitely renew at less than 5m a year.
For Chiesa there are no better options. He didn’t want to go to Roma and Napoli will probably play 352 under Conte which as we saw under Allegri, didn’t suit him. None of those teams are in the champions league and I don’t see EPL teams who are in the champions league bidding for him.
Given his stats, injury record etc, he shouldn’t be expecting more than he is getting now and should accept less. If he renews and has a great season then he has more options later. If he doesn’t renew he could be frozen out.