For me, my only choice for desktop, mobile, embedded and now even web is always Qt/Qml :), Qt is a c++ Framework available for large scale systems and embedded and now available to web using Web-Assembly, so one App Multi-platform :)
Using Qt Also allow me to extend my app in certain platform using their native toolkit, so i can write one app in Qt then add a java plugin for android or swift code to support certain feature in ios.
Even thought Qt is a C++ Framework I can write my app using only JavaScript or Python :)
-- Learn Qt here : https://qmlbook.github.io/
-- Qt is a free open source toolkit :) do not get back because the website is saying you have to buy it :)