@ndicosola
PowerApps is not your typical development platform - in that it is a no-code solution.
It does not deal with HTML in the way that you are suggesting, but rather with controls, connections, and actions.
However, it is VERY easy to create prototypes that are connected to data and to showcase them for further design work. Nice part is that they all "play" on the PowerApps player - which is available on all devices.
You might want to take a look at some of the Templates that are part of PowerApps as they are good starting points and will give a general idea on how things are connected together.
Hope this gives some insight.