I cannot vouch for every suggestion here, so please do your own research. Here my intent is to facilitate your search. My choices are the ones seen above. Keep in mind that libre software is usually more respectful of you as a user and owner of the software, as well as being respectful of your privacy. Having said that, not all of them have privacy as a main concern, so if that is important to you, please consider the section for privacy respecting software (those are my preferred libraries, alongside cli apps).
1) CLI Resources
2) GUI Resources
3) Privacy focused Resources
4) Video tutorials
1) CLI Resources
Inconsolation - library of cli apps.
Github - another library of cli app.
2) GUI Resources
Ethical.net - ethical library of alternative software.
FSF - open-source recommendations.
Gentoo - open-source recommendations.
Github - alternatives to bloatware.
Switching - ethical library of alternative software.
3) Privacy focused Resources
Dig Deeper - general library of privacy respecting software.
Prism Break - general library of privacy respecting software.
Shadow Wiki - library concerning emails, browser and phone usage (access the link via Tor).
The Big Tech Exodus - general library of alternatives outside of Big Tech.
EldritchData - If you wish to read more on privacy, please consider this website.
4) Video tutorials
These people provide good tutorials on a variety of open-source programs (primarily cli).
Brodie Robertson (his website) - software tutorials.
Bryan Jenks (youtube) - programming, productivity, and research.
Chris@Machine (youtube) - tutorials on nvim and programming.
Derek Taylor (his website)- linux distros, wm's and software.
Frederic Bezies (youtube) - introductory playlist about cli apps (in French).
Gavin Freeborn (youtube) - tutorials on groff/troff and other tools.
Gotbletu (youtube) - software tutorials.
Luke Smith (peertube)- software tutorials (and lifestyle).
Nicola Jelmorini (youtube) - introductory playlist about cli apps (in Italian).