Help needed!!!
I am new to a Sony Xperia XA2 Ultra with SailfishOS. Version 4.1.0.24 (Kvarken)
I am pretty familiar with linux, loved my N900 while it lasted and need to step away from Android.

Could you please point me to useful info to read (please no video, no youtube) about the basics of the system, like mount points, package managers, possible tweaks to the user experience et al.
The last time i used a rpm-based system was some 10 years ago... , i need to do some more reading about that, too.
If you could suggest some useful apps to add to the factory install, please.
Thanks in advance.