Startup and shutdown procedures can run into hundreds or thousands of steps, and a lot of digital tools treat them as one long form, which is why they lag on a phone in the field. The procedure needs to be broken into sections and individual steps so the operator sees the step they are on and what comes next, while still being able to jump around the full procedure when they need to.
Interface delivers procedures step by step on mobile for this reason, since an operator in the middle of a shutdown needs the current step to be quick and clear far more than they need to scroll through the whole document.