Irrespective of whether EU261 compensation applies, EW has a duty of care to honour the contract signed with the passenger to get OP to destination in a reasonable time. Duty of care always applies. Regarding price, the situation on the ground is going to impact prices because many people will be trying to get out on every flight possible, which ups the price quickly. So EW are going to find a similar price to OP. Although I agree that OP has done a reasonable solution to get to destination on time.

I wonder if it’s worth talking to a representative at the airport when the ticket is under airport control about changing the outbound flight to LCA and then refunding the original ticket for LCA-DUS bought as an emergency.