According to Viber site's documentation, a public account (PA) is required to work with its API: https://developers.viber.com/api/rest-bot-api/index.html. There is a standard form for registering these accounts by providing company's information, can be found at https://www.viber.com/en/public-accounts. But I'm just a developer who wants to try out the API using my own Viber account.
Can I achieve this without the creation of a PA?
No. Unfortunately its not possible to send bot messages to private account without public account. Its not possible to assign bot to your private account. Public account is in a way account for you bot. Viber needs to know who is sending message and to whom (PA account = bot).
Easiest way would be creating public account but not publishing it so that it doesn't appear in search result. While PA is not published you can add other developers / testers by adding participants using their mobile number and then granting them admin rights if needed.