please explain it more details what you have and what you want to achieve.
You have an Arduino Nano -
With an W5100 Module? or are are planing to use a GSM Module? Give links to your products.
Your HTML is hosted - on the Nano or on another Webserver?
You want to send data from the Nano to the Webserver?
You have available a SQL Server on your Webserver?
You have available PHP and have some knowledge about PHP?
You know how to retrive data from SQL and display that on a HTML page?
There is a complete solution to placing data on specific places on a web page in Arduino to Arduino via Serial
You will need to use either Serial (or Software Serial) from the nano.
JSON encode example also included BUT better to keep the msgs short and use CSV format
If your web site has the Flask Framework loaded you can use Python on the RPi and using the data from the Arduino display web pages on your web site. Your web site host may have instructions on how to load the Fask Framework.
Using your own RPi, you can setup a Flask server and use the Flask Framework instead of PHP. I am using Thonny on the RPi to write my Flask application.
Thank you everyone for all the answers. I realize i have not been good enough in my description regarding the remote sensor part. I am planning to connect to my "webpage" via cellular connection, i have not bought the sim module to my nano yet.