What is your favorite CI4-related learning resource?

Lonnie Ezell - Codeigniter4 Foundations

I am developing apps with CI for a very long time. Used CI, CI2 and CI3. Then I edited my CI3 with kenjis libraries, added .env support and many more. At one point I switched to Symfony 4 & 5 (never fond of with Laravel), as using an outdated framework made me unhappy. Then CI4 for comes and I immediately purchase https://leanpub.com/codeigniter4foundations which made me switched back to CI with v4. Still using some Symfony components with CI4. I think developing with CI4 is lean and straightforward. I love it.