PS4: How to get your hands on a PS4 with a 4.55 firmware or lower - Wololo.net
Increase your PS4's storage with an external hard drive - PowerUp!
PS4 System Software Update 4.5 - 12 Things You Need To Know - YouTube
According to theflow0 disclosure for BD-JB exploit, here is some table chart which exploit is working and which exploit is not working for each console PS4 and PS5 with their respective firmware :
PS4 system software update 4.50 is out tomorrow: here's everything you need to know – PlayStation.Blog
PS4 Jailbreak / PS4 Custom Firmware for Dummies - Wololo.net
How To Update Your PS4 To 4.05 Firmware Version - YouTube