[ofalkaed]

If your main computer uses linux you can use a script to start your writing app and have that script disable distractions for a certain amount of time. Simplest would probably have it start the writing program full screen and disable all WM/DE key bindings and hide any panels if it does not already do so in full screen so you can not leave full screen/open other apps until you quit the writing app. If you do not use a DE/session manager you can have an .xinitrc which does not start a WM and only starts the writing app, so when you want to write you log out and start X with the writing .xinitrc. This may be possible to do with a DE/session manager but I have very little experience with those so can not say.

If you just want to turn your old laptop into a fancy word processor just have your .xinitrc only start the writing app and you will not have access to anything else.

I suppose for these methods you would also need to have the script temporarily set your xdg default browser to something which is not a browser if your writing app uses the browser for help files since that would allow you to open a browser.

Why not just turn off all the devices and get out the pen and paper?

Edit: Probably easier to just have the script turn off networking than playing with the xdg defaults.