The Windows API through Delphi was simple and fast 20 years ago. Although the exe would take 400 KB space, so for smaller tasks I would bypass Delphi's stuff and call the Windows functions directly, and create 50 KB sized apps. (the A functions. Guess the Unicode W functions would already double the space)
But on Linux there is no way around Qt. (or Gtk, but the recent Gnome versions are horrible)
Although you could just make the Windows exe and run it through Wine. That is so simple to develop, and for any bug you can blame Wine.
Nowadays I use Lazarus. It is supposed to take the old Delphi code and create a native Windows,Qt,Gtk version from it. For Windows, it creates 2MB exes. Considering that Delphi made smaller files, it must be filling 3/4 of the file with garbage. The Qt,Gtk versions somewhat work, though Wine would probably more reliable