I checked this again, but it seems that the public directory has a bunch of code.
root@d66257ab-b6ad-4648-acf5-f1dbc2281a80:/app/code/7.2.7/public# find .
.
./oauth-callback.php
./robots.txt
./index.php
./web.config
./api
./api/v1
./api/v1/.htaccess
./api/v1/portal-access
./api/v1/portal-access/.htaccess
./api/v1/portal-access/index.php
./api/v1/index.php
./portal
./portal/.htaccess
./portal/index.php
./install
./install/img
./install/img/devices.png
./install/js
./install/js/install.js
./install/css
./install/css/install.css
./install/index.php
Do you remember what extension writes where? Is it in a subdirectory under public or does it write straight under public itself?