Hey Soma!
I am sorry that I hit a nerve with this introduction, but sometimes it is intimidating to ask "professionals" for step-by-step tutorials. Using the search here leads to great guides but sometimes I cannot follow along that easy.
I will post my stack when I'm home, but tried to find the php.ini in /etc/... subfolders in the meantime, but no luck.
Another proof you should not follow youtube videos for installing something. The authors are not going to support you.
Well, Youtube is a good guide (but it's just that, it should be verified).. My issue is with some of the things the Youtubers do that defy common sense (ie, as you pointed out.. using the 998 user for docker PUID's).... Unfortunately videos are more popular than written tutorials. The other big issue is, as the software evolves, docker containers change, etc.. videos are often not updated. Well, the creators aren't removing the videos because they want the views/ad revenue, but it leaves outdated info out there. Here, written tutorials are easily updated when things need to be updated.