GrapheneOS - maximum security and privacy for phones and tablets

• More Android apps than on other deGoogled OSs
• Very secure (hack-resistant) if correctly set up and used
• Easy to install to the few phones it accepts (some Google, some Motorola 2027)
• Beginner-hostile, complicated manual setup
• Good website and active forum

Notable mention for the beginner-friendly /e/OS (technically inferior compared to GrapheneOS, installable to more devices).

https://www.quora.com/How-does-Murenas-custom-e-OS-compare-to-Googles-Android/answer/Harri-K-Hiltunen

I haven’t tried CalyxOS yet. I had CyanogenMod for a few years before it was LineageOS.