I hear you that you want to keep your project free, but I'd also like to point out that it doesn't matter if your project is open-source or not to use Extension

I hear you that you want to keep your project free, but I'd also like to point out that it doesn't matter if your project is open-source or not to use ExtensionPay! For example, the extension NotionBoost is open source and also uses ExtensionPay for paid features: https://gourav.io/notion-boost https://gourav.io/notion-boost