How is the url(s) processed in the boards. Is the URL re-executed when the IDE is launched?
The EPS32 S3 super mini is not currently listed in the boards list. That board has been around for enough time that I would think that it should be on the list. I have the lasted version of the 2.0 IDE.
Welcome to the forum
Is there something special about the ESP32 S3 super mini that would mean that it would not work with a board described as ESP32-S3 ?
From the Boards Manager of my IDE 2.3.6 installation that has no URL for ESP32 boards in preferences.
I believe that they are now part of the core boards installed by default
The ESP32S3 Supermini is not listed in the ESP32 variants list provided by Espressif.
Unless the board vendor provides the URL for their own platform, you need to select "ESP32S3 Dev Module".
When you start IDE 2.x it will check if the installed platforms (board packages) are up-to-date. You can see that in the right bottom of the screen where a message like below pops up
Each platform (board package) has a list of boards; the maintainer of the platform (board package) decides which boards are in that list. In this case it's Espressif so you can contact them to add the board; if they will honour the request is an other question. The file where the boards are "defined" is boards.txt.
You can also add it yourself; if the board is totally different from anything else you will need to know exactly what you're doing. If the board is like the "ESP32S3 Dev Module" mentioned above you can make a copy of that entry in the boards.txt file and give it a new name.
Note that an update (by Espressif) of the platform (board package) will wipe those changes.