Gazette started as an internal tool in my previous startup (AdTech related). When forming our current business, we very briefly considered offering it as a raw service [1] before moving on to a holistic data movement platform that uses Gazette as an internal detail [2].
My feedback is: the market positioning for a service like this is extremely narrow. You basically have to make it API compatible with a thing that your target customer is already using so that trying it is zero friction (WarpStream nailed this), or you have to move further up to the application stack and more-directly address the problems your target customers are trying to solve (as we have). Good luck!
[0]: https://gazette.readthedocs.io/en/latest/ [1]: https://news.ycombinator.com/item?id=21464300 [2]: https://estuary.dev