Integration of GPTs own trained agent (openAI) with OneBox through the API of the "GPT chat" component

Good day! I would like to learn about the possibilities of integrating external agents of ChatGPT (OpenAI) into the OneBox system using the API https://1b.app/ua/solution/gpt-chat-astelit/. I mean the situation when there is an already developed and trained agent (GPTs assistant) that operates on the corporate database, and I want to connect it to OneBox. Does your GPT chat app's API support this kind of interaction? The main purpose of integration is to ensure the connection of this agent with various communication platforms (Facebook, Telegram and others). I would be grateful for information about the possibility of connecting through your API to applications that develop the logic of chatbots, or to bot constructors https://1b.app/ua/app/bot-constructor/, in particular for Telegram. Interested in the following: 1. Does this application "GPT chat" support the integration of external agents? 2. What API integration can be built/extended to connect an external agent? 3. Is the existing application paid? 4. Is it possible to connect the agent's GPTs to the messengers so that the information from the messengers is sent to the agent, is formed there and transferred back to the messenger? Any information to help implement said integration would be greatly appreciated.