The maximum battery save mode on Samsung (or maybe on all android devices?) does just that - you can set the limit on which apps can be opend. Turn the display to greyscale. Homescreen only shows like 8 apps.

I think for most people, just putting an extra step between you and whatever toxic app(s) you have can be enough. It mostly works for me, and as an added bonus you get insane battery life. I would try that before buying a new phone.