There are a few ways to get the transcript from Google voice, for free.
1. Install the Google Voice App and set it to only voice mail:
https://forums.androidcentral.com/e...android.apps.googlevoice&hl=en&token=FZGvgLyH
Each time you open the app you'll see all of your voicemails transcribed in there and you can listen to it from there. The cons of it are, the app is a bit outdated and you can only listen to voicemail through the earpiece and you can't easily switch it to speaker phone. If you switch it to speaker phone in the settings, then it will always play through speaker phone. You can still listen to the voicemail through the dialer, it won't affect it there. So you can use the dialer to listen to voicemails and the Google Voice app to read the transcription.
2. In your Google voice settings, go into the General settings and check off the box to email you the transcript or text it to you (or both). You'll get the transcript sent to it the second it's done.
3. Put a shortcut in your Browser on your phone to Google Voice and go online to view them.