@Suty +1 another interested premium user.
Unsure if you're aware but there is a large base of potential future Windy premium subscribers if you made this available: https://analytics.home-assistant.io/ (and these stats are only of folks who have opted-in!)
In case you were not aware, Home Assistant ranks as one of the top open source projects on GitHub: https://github.blog/news-insights/octoverse/octoverse-2024/#the-state-of-open-source with extensive Developer Documentation ( https://developers.home-assistant.io/docs/development_index/ ) and a big community of developers who typically take care of all the integration work to get it all up and running in HA in their own free time. It would just require this affordable access to your API.
Any other convincing you need?