1. Go to the Google Takeout website (http://takeout.google.com) and sign in with your Hangouts account credentials. 2. In the list of available data, select "Hangouts" and make sure all other options are deselected. 3. Click on "Next Step" to proceed. 4. Choose the specific Hangouts data you want to include in the download. You can also select how frequently you want to download backups, such as once or every two months. 5. Click on "Create Export" to initiate the export process. 6. Google will now start preparing your data for download. Please note that this step may take some time, ranging from several hours to even days, depending on the amount of data being exported. 7. Once the export is complete, you will receive a notification. Access the exported data and locate the attachments you sent through Hangouts. 8. Download the attachments to your device by clicking on the respective files or folders.

By following these steps, you will be able to download the attachments you sent via Hangouts using Google Takeout.

To switch from Hangouts to Google Chat, you don't need to manually transfer the data as conversations from Hangouts are automatically migrated to Google Chat. Additionally, you can search for your messages within Google Chat.