Hi,
I am an experienced chrome extension developer with 6+ year of experience in development, I have gone through your requirements and from that, I got to know you are looking for a desktop based software solution which will work exactly like the extension does but it will charge a monthly fee.
I can build the desktop app for Mac && Windows with no extra cost in Electron which is a cross-platform desktop-based software development solution. It is robust, fast and many big applications have been developed using it.
I am very confident that you will get the best quality and result you are looking for. I will request you to come on the chat and we can have a detailed discussion on the project.
Thanks
Rupa