Fellow "wrote my own generator" person here (I built the codegen system Stripe uses to generate their API client libraries). Sounds like you've got a pretty neat system too, hadn't thought of some of these approaches.

We had a similar story – after looking at the OpenAPI Generator and other options, we ended up making our own in JS from the ground up, more or less (it used the internals of prettier to generate pretty code, especially example snippets for docs, across languages).

I'm now starting a company (https://stainlessapi.com, mentioned by OP elsewhere on this thread) to solve this problem more generally. If you ever get tired of maintaining this system (which may not happen, it does sound fun/interesting) or want broader language support, and are open to a commercial solution, drop me a line: alex at stainlessapi.com

(open invite of course – and also always happy to just chat codegen things, it's a neat little niche)