It's possible to export your Streak data to a spreadsheet and then to import that data into Sortd using Zapier.
1. Export your data from Streak.
https://www.streak.com/post/export-to-google-sheets
2. Upload the spreadsheet to your Google Drive.
3. Create a Zap to import from a Google Sheet into Sortd. Use this template to start:
https://zapier.com/shared/18e9c2db2f8cd1a5541c17860b60d8972cf0394c
4. After setting up your Zap transfer the existing data to Sortd
Note: You will need to be on Zapier's Pro plan. If need be you can upgrade temporarily and after your data is imported cancel your premium Zapier subscription.