A good tech or engineer can make such a thing like https://www.unifiedremote.com/tutorials/how-to-create-a-custom-ir-remote that would have ONE button on it to do what is needed to get the input to what you want. An even better tech could tie this to power on so it happens automagically.
http://www.remotecentral.com/cgi-bin/mboard/rc-custom/thread.cgi?13114 shows this is not an unique request.
My father has dementia and can't manage the remote provided with a Samsung TV. We bought him a flipper remote, that only has volume, on/off and 25 pre-set channels. Recommended for dementia patients.
We bought him a Sky package with free Samsung TV.
We can't set up the TV to go automatically onto HDMI without going through Source. We contacted Samsung UK and they told us the free Samsung TV was a model meant for hotels and businesses and we'd have to contact Samsung in US direct to find out. We haven't managed to get hold of them and dad can't use his TV, sadly.
The model of TV is HG32ED450SW.
Thanks for any assistance that you can offer