We've made some enhancements [1](e.g. OpenAPI 3.0 support) to the Python Flask generator in OpenAPI Generator. For aiohttp support in the Python Flask generator, I don't think anyone is working on that. Please let us know if you've time to make the contribution by opening an issue to start with and we can work with you to make it happen.
(OpenAPI Generator is a fork of Swagger Codegen. For the reasons behind the fork, please refer to the Q&A [2])
Sorry to hear your negative experience with Swagger Codegen regarding the PRs. Having been "managing" the project for a few years, I agree with you that I've not done a very good job in reviewing and merging all the PRs (239 open PRs as of today) contributed by the awesome community.
Myself and 40+ top contributors have decided to fork Swagger Codegen so as to maintain a community-driven version called OpenAPI Generator [1] with a better governance structure to move the project forward. Now there are 10+ core team members and contributors with proper rights to merge PRs so I think we've better PR management in OpenAPI Generator. Please refer to the Q&A [2] for the reasons behind the fork.
For TypeScript generators, we've recently added the TypeScript Axios client generator [3] and there's an ongoing project to consolidate the TypeScript generators into one [4]. Please check these out and let us know if you've any feedback.
We hope you will find OpenAPI Generator useful in your projects.