Yeah, making a good SDK for every major language would be an absolutely Sisyphean task with negligible returns - it'd be great to have at least one solid reference implementation though.

e.g. a reference implementation in Ruby if they're a Ruby shop, a reference implementation in Java if they're a Java shop, etc.

I wonder if you can generate a "good enough" API client to start out with using say, OpenAPI and then tweak it to suit your needs?

Then again, maybe this is where something like gRPC would really shine compared to REST APIs - I'm not sure, but, it seems like an area that could be improved significantly.

Your startup sounds promising, and hopefully it helps to simplify things!