This looks pretty sweet; I've spent a lot of time the past few years writing a LOT of OpenAPI specifications and the thing that gets tiring is all of the boilerplate with each bit of the definition (paths -> get -> responses -> 200 -> application/json -> schema). It gets so exhausting and turns into nested YAML soup pretty quickly. Having better support for multiple files will also be nice; _technically_ you can split an OpenAPI specification into multiple files but the tooling never quite deals with it properly.
I'll definitely be keeping an eye on this; looking forward to TypeScript code generation! One of our main use cases for OpenAPI is to document our models and then generate TypeScript types from them (that we then use in Node and React apps)