Gave it a try in Linux since I launch it from a terminal. First, it doesn't allow you to export and this verbiage shows up in the terminal window:
[ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: UnimplementedError: Sharing files not supported on Linux
Next, tried to do an import, but all it will let you do is select folders, not [the CSV] files.
Full set of information from the terminal window from launch, to attempted export, to attempted import, is shown below.
robert@ASUS-TUF-Gaming:~$ avarex
Gtk-Message: 19:27:56.328: Not loading module "atk-bridge": The functionality is provided by GTK natively. Please try to not load it.
(AvareX:28773): Gtk-WARNING **: 19:27:56.399: GTK+ module /snap/avarex/56/gnome-platform/usr/lib/gtk-2.0/modules/libcanberra-gtk-module.so cannot be loaded.
GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported.
Gtk-Message: 19:27:56.399: Failed to load module "canberra-gtk-module"
(AvareX:28773): Gtk-WARNING **: 19:27:56.400: GTK+ module /snap/avarex/56/gnome-platform/usr/lib/gtk-2.0/modules/libcanberra-gtk-module.so cannot be loaded.
GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported.
Gtk-Message: 19:27:56.400: Failed to load module "canberra-gtk-module"
[ERROR:flutter/runtime/dart_vm_initializer.cc(40)] Unhandled Exception: UnimplementedError: Sharing files not supported on Linux
#0 SharePlusLinuxPlugin.share (package:share_plus/src/share_plus_linux.dart:22)
#1 SharePlus.share (package:share_plus/share_plus.dart:102)
#2 _LogbookScreenState._exportCsv (package:avaremp/logbook_screen.dart:141)
<asynchronous suspension>
** (AvareX:28773): WARNING **: 19:28:21.513: atk-bridge: get_device_events_reply: unknown signature