Thank you for your question.
I am not sure if I understood your question but it seems you want to grant access user(s) or group(s) to a particular branch. If so, I would suggest you on referring to Using branch permissions documentation for further information.
Regarding on the SSH Keys, you can grant read/write access to a particular repository and/or project. Once you do that, you can review the documentation above to restrict access to branch(s) to user(s) or group(s).
If you find this answer useful, I would kindly ask you to accept it so the same will be visible to others who might be facing the same issue you have inquired.
Thank you for your understanding.
Rafael P. Sperafico
Bitbucket Pipelines helps me manage and automate a number of serverless deployments to AWS Lambda and this is how I do it. I'm building Node.js Lambda functions using node-lambda ...
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