Does that all really mean, mounting / accessing files from a Porteus XFCe Linux to/from an android out of the box without tweaking the XFCe Porteus somehow has zero chance in working?
I am not rich enough to afford Samsungs, I tend to buy Mediatek chipset phones from China.
Also its not clear to me, if you mean just your removeable sdcard or your internal storage (balance of ROM after system)
1) Go to Thunar and check you have in Preferences setup mount removable media either automatic as prompt
---I am on LXQt but the file manager preferences are similar
2) In your phone, watch your notifications please. My phone allows swipe down from the top to re-visit any you have missed.
The phone may have timed out on giving you MTP. In which case simply pull the USB cable and re-insert.
3) Forgive this bit, some phones expect USB Debugging to be turned on....and have set it to default OFF.
So if you see the notification that your device offers MTP, camera etc then ignore this advice
---Otherwise you need to turn it on. Most phones require admin rights to do that.
Go into system settings and look for "Developer Options"
If already there, Go to the section called Debugging and touch it to enable it please.
(b) If you can't see Developer options in settings you need to turn it on.
some phones allow this by touching the about phone about 7 times, and often give a warning that you are about to enter developer mode or admin mode etc etc.
4) the other option, without removing your sdcard, is to look at adb in Linux thru android-tools XZM and setting up an udev rule
but that is a much longer process and may be beyond your time needs?
I have done it on another distro but not yet done it on Porteus.
adb is mainly used to interact with naughty system settings and can access the system not the removeable sdcard
I am too lazy to duckduckgo your make and model to see if there are any issues, I shall wait to see if above is of any help