You're absolutely right cause if human error is not put in check it may affect the OP fund and running the full node also require some computer skillls when implementing the script. However, the best choice for the OP is to make use of https://btcpayserver.org/ and OP still need to do his own research either.
If you can't write a simple script to do the actions you need to be done once a payment is coming in (or confirmed), you are - by far - not able to host a lottery site.
Running a full node is not risky at all.
Obviously you have to check your implementation. Setting up some triggers is not as hard as setting up the rest of the backend of a crypto lottery site.
The choice purely depends on what OP needs and wants.
