This has been brought up in the past but I'm a little stunned that it hasn't be requested more frequently.
I have a requirement to be able to provide a simple one or two step process to allow individuals that have been provided with USB keys to have access to a number of accounts and secure notes.
The fact that the portable version brings up a "nag screen" requiring the user to specify a path every time it is ran is unfortunately a really terrible blocker for me being able to move to Enpass from IronKey's (hardware encryption.) It adds an unnecessary step that really hurts the simplicity of use.
Some ideas on implementation:
If the config file is found in the current working directory of the executable (which should be a dotfile on OS X and linux in my opinion e.g. .enpass.conf) then parse out a KVP from the config file that specifies a path (relative or full) to the walletx.db for each platform release.
OSX/Windows FAT16/32 config:
This would hide the config (if it were a dotfile) and allow a USB key to store configuration on the relative or full path to the walletx.db.
This would allow for an extremely clean portable installation that would work on partitioned keys and across all platforms as far as I can tell, and eliminate a step that should be totally unnecessary (prompting for the path to the walletx.db and storing a recent paths file in the home directory.)
If these changes were implemented I think you would find a surprising increase in downloads over time.