Not everyone has this luxury. My office has a shelf of candy that's restocked every couple days. I think I've put on at least five pounds since I joined two months ago.
My point here is that the modern world almost seems to be conspiring against healthy living, both mentally and physically, so whatever you have to do to be healthy is worth doing. I've played around with various web blockers, and finally got around this YouTube on phone problem by installing both a blocker app and also using the adb command line tool to manually edit the hosts file to also block YouTube in the browser which required unlocking the bootloader and accidentally wiping my phone. But now, I can't watch YouTube on my phone and it's wonderful to not have that temptation now.
I don't know what the answer is to community junk food. I'm at home with parents this week and I was gifted junk food, which I was grateful for but also a little sad about.
Can you make an app that appeals to my emotional lizard brain and prevents me from eating candy and browsing the internet? That's something I'd pay for.
Fortunately, I also work remotely, and am much more judicious about my snacking choices.