Never be able? C'mon, your app is basically one of the Qt samples dude.
But UI is not essential for a functioning app, and if the time costs of building a good UI are too high (a lot of new learning and problem solving) I'll spend less time on it.
What "sample" are you talking about? Is this the kind of thing you're comparing my app to? https://doc.qt.io/qt-5/examples-graphicsview.html
https://doc.qt.io/qt-5/qtdoc-demos-photoviewer-example.html
(Edit: by no means I'm saying that your work is trivial to replicate, apologies if this comment came across like that - just wanted to point out that there's more to Qt than Qt Widget.)
The original reply I made was to point out that startup costs decrease number of people starting. Unless you know Qt already, your first project will take much longer than using technologies you already know. It's not at all clear how long learning would take.
I know I can climb the mountain, but I'd rather not. This isn't to discourage others from doing it, it's to explain to those who don't understand why many people prefer to stick to Electron.
Simple QML viedo player.