Ok, I hope I am not regurgitating the old, I want to use a POSIX filesystem on my memory card, as far as I can tell from here it should all work.

My main question is what is better, btrfs or ext4 and even more importantly should mounting options like noatime be used or not...

ext4 obviously is more stable on the other hand jolla itself uses btrfs for most of the filesystems so clearly it's stable enough