Obviously I might be a bit bias, but I'd personally skip learning Qt/TornadoFX and just focus on Compose Desktop. But I suppose that's the type of sampling bias you get for asking this question in a compose-desktop channel 😛
Cheeky responses aside, I personally believe Compose has a very bright future and so that's why it's what I would focus on. Having said that, the reality is that it's more important that you learn than it is what you learn. Technologies come and go and don't make a whole ton of difference to your career. As a novice, your goal should be to learn to build things, and that skill will mostly transfer regardless of which technologies you end up working with in the future. You should pick whichever technologies excite you the most, because that will keep you engaged and learning.