There are many heated discussions about Qt licensing which can be found on the qt-interest archive.
What you will come away with is that Qtc defines OpenSource as “everybody must buy a license but please continue working for free on our product.” This is why they got rid of LTS OpenSource.
The general rule is “if you have to ask what it costs you can’t afford it.” The last project I was on using Qt (which was a few years ago) had to pay north of $600K for 3 (might have been 5) developer licenses and royalty free distribution.
Since then I haven’t encountered a single embedded systems project were Qt was even considered. There are much better and more cost effective options out there.