I’ll start by plugging Harvard’s free courses catalog as well as Udemy
Edit: Gonna add 2 more I remembered-
Blender - I wish I had more time to learn it, but I did start the infamous “Donut Tutorial” once!
Watch Cartoons Online - Lots of good older stuff!
https://calibre-ebook.com/
Own your own ebooks. Make sure all devices work with whatever format you need.
Good call on that one, calibre is one of my favorite pieces of software. I, uh, acquire ebooks through creative means and use calibre as both an ebook catalog and format converter to then load them onto my kindle.
I try to support publishers that give you the full ebooks like baen library.
Calibre helped me back up my entire amazon library in a way my kobo can now read instead of just kindle. Both are excellent devices, but I wanted a backlight after 7+ years with the same ebook reader. And I’m not about to purchase all those books aain for the privilege of using the kobo bookstore. Plus Calibre makes it so no matter what you get (pdf/ebook/proprietary format) you can get a good old fashion ebook format for future preservation.
You should probably note, the functionality you’re describing now requires modding/plug-ins and not the “search and enable” kind, the download from third party sites and run random install scripts kind. It also since February requires you use your Kindle to download and copy every book you own (a chore if your family buys a lot of pulpy urban fantasy novels)