Raspberry Pi Startup Code Execution

I have three python codes in my raspberry pi which needs to be executed at the startup (when the pi is booted). one code involve USB camera, another codes is related to playing video via VLC media player and the third code is a counter that sends the data to a cloud. All the codes are working perfectly, they are even working when they are executed simultaneously, but the only thing is that the USB camera code is not working at the startup. If you want me to chat with you, start the bid with "pi" We have tried a lot of methods, but still no success, I believe it is because we are using raspberry pi 5, there are limited resources and libraries for it online. Please help me with this.

Thank you.