Arduino Updater

I have a question about the Arduino tool chain.

What I’m looking for is a simple way to update the SW (the Application:Sketch Part, not the bootloader) of an Arduino UNO WIFI Rev2. I know the IDE is capable of doing that out of the box but I look for a way to handout some binary representing the Arduino SW and a PC SW Tool that flashes that binary to an Arduino connected to the PC via USB without much hassle.

Background for my question is that I created an Arduino project to build a Christmas preset (Arduino UNO WIFI Rev 2 with some Sensors) for my father in law (80+ Years) and would like to send him an SW Update for it that he can apply by himself (no personal contact to support, Corona, you know...). Now, he is quite into Computers, can handle eMails, Weblinks and might be able do download and start an single PC Programm, but installing the full IDE, including my sketch sources, compiling it... I guess that is too much.

Questions: - Where is a Arduino SW binary located in IDE Directory that results out of a successfully compiled sketch? If I compile a sketch, where is the binary output located on the PC?

Is there a simple PC Tool that can be used to flash such Arduino SW binary to a connected Arduino? I guess such tool is somehow part of the IDE... but I could not identify it...

From Arduino ver 1.6.5 has a new command: Under the Sketch menu, select Export compiled Binary, then Show Sketch Folder. There it is.

Great, thank you!