In Flutter, there are two main options to share content on WhatsApp:

1. share_plus

✅ Allows sharing text, images, and files.

❌ Does not support opening chat with a specific WhatsApp contact.

❌ Shows a share sheet — user has to manually select WhatsApp and contact.

2. url_launcher with WhatsApp deep link (https://wa.me/)

✅ Allows opening chat with a specific contact using phone number.

✅ Sends pre-filled text message.

❌ Cannot attach files/images — only plain text or file links.

🔚 Conclusion:

You can’t share both file + text directly to a specific contact using Flutter unless you use the WhatsApp Business API, which is server-based and not suitable for typical mobile apps.