I will use a free UI toolkit when I can. Qt will kill itself with their current pricing model.
Automotive is moving towards Android. Qt is not good for medical either because it is not really certifiable.
The trend is already visible with SaaS, Cloud, IoT,...
Qt is certainly certified for medical use, https://www.qt.io/qt-in-medical/.
I have hardly seen any big Android Auto adoption.
The biggest foe of Qt in Automotive is Web stack.
I have seen two very big Qt projects being cancelled due to Android. Not the Android Auto app but native Android for IVI.
I don't see any indication of your vision for shareware. The trend is towards more and more software being licensed under licenses such as MIT.
Which is exactly my point.
Give the tip of the iceberg for free, charge for everything else and give as little back to upstream, if anything.