Also a customer here, DatoCMS is fantastic product. We run hundreds of sites on their platform. Their team also works with you on pricing as you scale.
This reminded me of the Knowledge Project podcast with Dr. Rhonda Patrick on certain biomarkers, including omega index as an indicator for longer life span.
We've been using Mercure for 3+ years in production. It's been pretty much set it and forget it. Maybe once a year do we have to maintain the server e.g. clear up space, but overall has been great for our use case (which does not need full pub/sub).