Thanks for being a Visa Developer Community contributor every time you post questions and solutions to this forum! Before you move forward with Visa Direct, can you please let me know if you've read the Visa Direct documentation via this link - https://developer.visa.com/capabilities/visa_direct/docs?
There's definitely some important information on the Visa Direct documentation located in the first few paragraphs, that discuss Visa Direct requirements and it's shaded in yellow.
After reading the documentation and if you meet the requirements shaded in yellow, then please fill out the Visa Direct Program Implementation Questionnaire, and submit to the email address listed on that form.
You can create a app that uses Visa Direct API on developer.visa.com and use the API in sandbox mode. To take your app to production you would need a sponsor bank.