Application stack for home IoT + DB + Visualization?

Question

Database

Interested in possible options for a set of applications for the implementation of a simple smart home + data archive from sensors with visualization on the Internet.
At the same time, I would like to devote a minimum of time to the part posted on the Internet, I am interested in ready-made free solutions.
Plus, without using external access to the local network, i.e. data transfer to the database must be initiated from the LAN.
Estimated stack:

• Sensors: Arduino, ESP8266, etc. with LAN access
  
• MQTT broker - Mosquito in Jail on FreeNAS server
  
• Local interface to MQTT - as I understand it, there are thousands of them, both for android and other systems
  
• Database question + online visualization. The simplest case that I found on the forums is submitting forms and filling in a Google spreadsheet with data. Everything is fine, the data can be charted and shared, but perhaps there are more convenient free cloud databases with beautiful data visualization (selection of the desired trends, time period for visualization, measurement according to the schedule, etc.)
  
• Do I need some local application between MQTT and the Database that will push data from messages to the database? Or does MQTT know how to do this?
  

Structural scheme desired:

PS: I probably wrote something very stupid here, I have almost no experience in IT, correct me if that?

Answer 1

I use Cayenne while the flight is normal.