Working with TG bot in PHP

I will start immediately with the project color. Gray, to put all the points at once. 
The bot code is somewhat cluttered because almost everything is in one main file webhook.php (more than 16k+ lines of code), and sometimes the function.php file was previously required for updates.
1.  Adding support for managing requisites, displaying them to users with a certain turnover, as well as functionality in the admin panel for working with requisites. I will describe in more detail how I want to see everything in practice. 
2. Integration of a simple API. (The idea of how it should look: the user clicks on generate QR (button), enters the amount, receives a response from the API - then displays it to the user). Also, the history of these generations for the user themselves.