A really important part of being an entrepreneur is knowing about different tools and how to use them. It's a great idea to the explore app builders and programming languages other than App Inventor!
However, as outlined in the submission guidelines, you need to submit source code with your submission. If you can't submit source code (that a judge can test) with the app builder you are using, then you won't receive full points for your submission.
If you have questions about what programming languages you can use, check out this article.