No results for my search? Let user see no results or not allowing them to see the results that are not available?

I've been working in resolving an issue for the platform I work in but I'm a little stuck with solutions I was wondering if you guys could give me some advice on how to approach this. So, I'm working in a data company, specifically Short Term Rentals Data (ADR, Revenue, Occupancy rates), this means our users are looking for data related to the area they have properties or the area they are thinking on investing in a property. Now the problem is we don't cover all areas yet.

The way an user finds an area right now is through a search box and our first attempt for handling this was to just allow the user to search for areas we have in our data base, which of course lead to lot of angry users saying they couldn't find their areas and also us being unable to know how many users were looking for results we don't have.

So my idea is to allow users to search for any area they want and then if we don't have the area showing a message 'we don't have this area yet' and then maybe even having some kind of 'related search' actions. My team thinks this could lead to users searching a lot of mistaken areas and we not Preventing it.

Do you guys have any idead on how to solve this?