This is actually something we're working to improve at the moment, as the process at Intercom hasn't been that standardised in the past.
Historically at Intercom, betas were driven by the product team and wholly focused on collecting product feedback (often via research interviews and feedback through our messenger). As our PMMs work closely with PMs - and are often involved in sending the messages to beta participants - the feedback from these betas would be shared with PMMs and we'd use it as relevant to inform messaging and launch plans.
However, because we also want to leverage betas for things like customer testimonials and messaging feedback, and because our customer base has over time become more upmarket (which tends to mean beta featuress need to a bit more 'baked' before customers will use it), we've started introducing new processes to betas. This includes things like having them being more full-featured before rolling out as a beta, starting earlier so customers have more time to see the results of using a feature (which aids us with testimonials), and sales and PMM being more involved in choosing the beta audience. Things like ideal timelines and how to standardise dissemination of the information is something we're still working on - maybe we'll write a blog post when we figure it out!