The prefix 0 already makes the file to be sorted at very first in Nautilus. What can come before the very first file? No files could, except directories. This is true regardless of locale in use.
File naming
In the following example, I first created an empty text file named apple.txt then made multiple copies and rename each of the files by adding single character prefix. I have used only most compatible alphanumeric characters: 0 A á _ - and apple for reference.
Note that á is the second letter of Czech, which is found in this article section on Wikipedia. The first letter seems to be same as English: A and a.
File sorting
How will Nautilus sort these files in different locale environment? Turns out that it is similar but slightly different. See the following screenshot for comparison.
Nautilus sorted files in English environment en_US.UTF-8 like this:
apple <-- directory
0apple.txt
Aapple.txt
áapple.txt
apple.txt <-- original file without prefix
apple.txt
_apple.txt
-apple.txt
Nautilus sorted files in Czech environment cs_CZ.UTF-8 like this:
apple <-- directory
0apple.txt
Aapple.txt
áapple.txt
apple.txt
apple.txt <-- original file without prefix
-apple.txt
_apple.txt
In both locales, there is no change in order of directory and top 3 files when viewing as list in Nautilus. This already shows that no alphanumeric character can appear before 0apple.txt.
Workaround 1
One way is to create files with name other than existing "apple" with same prefix 0 that precedes the existing one. Creating 0aaa.txt will come before 0apple.txt and so forth.
Using this workaround, the files are sorted like this:
0.txt
0a.txt
0aaa.txt
0apple.txt
...
This way, the file 0.txt would be the very first file to appear in Nautilus. No other files can come before 0.txt, unless user want to create a file name .txt (using only a space character).
Workaround 2
Say if apple is already the very first file that can exist and user insists to not rename apple, there is another way: Rename the existing file with higher number prefix from 0apple.txt to 9apple.txt. This will allow other files with lower number prefix 0* to 8* to appear before 9apple.txt.
Using this workaround, the files are sorted like this:
0mango.txt
1kiwi.txt
2orange.txt
...
9apple.txt
...
Workaround 2 is unsuitable, if the 0apple.txt as whole cannot be renamed for whatever reason. Workaround 1 will be more effective since 0.txt will always appear before 0mango.txt or other file names that user can think of.
How did I test
In my testing, only essential locale packages were installed to prepare Czech environment for running Nautilus in Ubuntu. The quick way to run program in other locale by LANG=<LOCALENAME> nautilus command didn't work. Hence, the following steps.
Install these packages language-pack-gnome-cs language-pack-gnome-cs-base language-pack-cs language-pack-cs-base via APT in Terminal
Go to System Settings > Language and Support
In Language - Language for menus and windows, drag the entry named čeština (word for "Czech" noted by Wikipedia) to above English
Log out and log in again to take effect
Tested using Nautilus 3.14.3 in Ubuntu 16.04 LTS (Live).
TL;DR Filename with prefix 0 makes the very first file in Nautilus. No other files, except directories can appear before the very first file.
xdg-open uses xdg-mime to determine the type of object to open and then searches for the default application for it.
$ xdg-mime query filetype $HOME
inode/directory
$ xdg-mime query default inode/directory
nautilus-folder-handler.desktop
You need to set default application with nemo.desktop file. You can find it in /usr/share/applications. Then
$ xdg-mime default nemo.desktop inode/directory
And try open any directory with xdg-open.
Best Answer
It sounds like you need to meet to DoubleCommander
It have:
Alternatively you can display the name with the extension and the extension column
Also you can change the fonts in the config
You can add a hot key to edit the path or, from the first row, press F2.