[Adoby]

No, it is not simple at all. It is very complicated, the documentation stinks and the learning curve is ridiculously steep. It is intended for makers and DIY. That means that an extremely poor developer experience is expected. A lot of libs are available, but you need to find them. And then check to see if the lib work as you expect them to. And possibly fix them. If you think that sounds fun, then go for it.

There is, as far as I know, no support for dragging. Just up to two simultaneous touch presses. You may be able to use that to create some lib to support dragging, perhaps. Or perhaps someone else has already done that?

Take a look at the UIFlow documentation or the web app to see what GUI functions are supported. Not a lot...

I don't expect to do very fancy stuff with this device. I simply intend to make some panels with buttons to press, some very simple gauges and some simple text labels that depends on what some MQTT broker in the network says. If I had more experience and knowledge, I most likely would be able to do much, much more.

Start with something simpler and cheaper. Build up an infrastructure. Get something running on an Android phone or on a RPi Pico? Setup a MQTT broker and node-red on a RPI4. Control a smart light with MQTT messages.