I guess hindsight is 20/20, but even though I think OCaml is a really endearing language, I would not build my startup on it, for the reasons everybody else is saying! I don't have time to shave yaks with respect to database access, cloud storage, etc.

The savings in just going over to GCP or AWS and filtering your "potential languages" by the list of supported languages seems impossible to overestimate.

If you want something with more safety machinery than Go (and I get it, so do I), I think your real choices for a language that needs to interact with cloud providers are something on .NET, or something on the JVM - you pick one, and you go solve your actual problems instead of having to write your own stdlib.

I'd be way more open to experimenting on the front-end with buckle->rescript or similar, where I'm leveraging existing JS libraries and don't have to worry about high quality database drivers.