Hi,
First of all, let me explain what i understand & it's feasible solution.
Assumption:- I assume you want scheduling even when system is Shutdown.
Comment:- Chrome extension/ Desktop application works only when browser is open. It will auto post when browser is opened & internet connectivity is available.
To auto post on scheduling independent. We need server and CRON job need to be setup. otherwise it can not be done.
⭐⭐Past Chrome Extensions⭐⭐
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https://www.freelancer.com/projects/php/Chrome-Extension-with-basic-scraping/
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⭐⭐About Me⭐⭐
I am Sr. Open source developer having 6+ years of experience. I have much experience with native jquery, typescript & browser extension development. I am full time available and can do it quickly. I believe my abilities would be perfect for your venture.
Eagerly waiting for your reply.
Thanks
Nitin Saluja