Q:

Is it possible view the nearby devices? 

I'm trying to make a app for report the human interaction because the virus, I just want to know if it's possible for follow a way, I know that exist google nearby, but that requires that both devices has the same app installed and it's the same with the bluetooth or ble, so what others tools could be usefull for make my app?  Thanks. 

A:

It depends on your approach but ble has the functionality to scan for discover able advertisement from other devices. 
This means you can see and store another devices address(ble) to a list / database.  The beauty of this is ble only works well within a short range distance though you can filter by distance crudely by the RSSI.  The RSSI is received upon scanning it is the received power from another device. 
So for a contract tracing app you will need to develop a system which advertises a ble packet and along with the app scan for ble packets. 
Then if you find via your scan another device, you add it to your database. 
Next you need to check your database "for the virus" this means looking up a backend system where you store the ble addresses of people with the virus.  Then the user checks the database with their list of addresses, if there is a match of addresses, then you have come into contact with the virus and should get treatment / self isolate.  Just what ever your geographical location laws are. 
So simply put you need:

App for both phone
Back end database
Database on each phone of addresses found
Ability to send out address via an advert(beacon)
Scanning of beacons
Checking database(backend for virus)
Uploading to database(Stay you have it, don't have it or are cured)

Hope this helps.