It is possible to use google speech to text api via audio streaming only using one of these frontend technologies: react or javascript? I'm trying to create a react form where fields can be filled in by text or by voice. What I'm looking for is a way to integrate this voice streaming with google API without the need for backend.
No. Since you have to keep your credentials secret, you should only interact with their API through some sort of server (that way the client doesn't have access to your Google account and/or full access to Google's API). You can do this using NodeJS as shown on their docs. You could then create your own API using something like Express, that React interacts with.
It would be possible to interact with their API from JavaScript, but you should not do it. You will have no control over users abusing the API you pay for.