Thanks for the info, especially your "I use it regularly, it works great."

>iPadOS is restrictive, that is either a bonus or a curse. It does let you focus more on tasks

I used to compress my browser's executable as a way of "disabling" it. That stopped working smoothly after MacOS locked down the /Applications directory, but I found other ways to disable my browser: on Gnome now, I wrote a command that is easy to invoke and that removes browsers from "the Dash" (Gnome's analog to the Dock). (The command is implemented with `gsettings set org.gnome.shell favorite-apps`.)

Note that this method of "disabling" the browser does not prevent me from starting the browser with a command line entered into a terminal window, but it does stop me from starting the browser in a way that requires no thinking from me (i.e., the way I habitually do it) which turns out to be enough to prevent me from wasting time in the browser.

Being able to easily "disable" the browser (or more precisely, to easily arrange it so that I need to think in order to switch to a browser window) has significantly reduced the amount of time I waste online. Of course, there are times when some pressing task requires use of a web browser (which might coincide with one of the times when my ability to resist the temptation to waste time on the web is low) but in my life, those times are rare.

Yes, iPadOS offers a way to disable Safari, too, but the difference is that doing it on iPadOS requires many steps, and it hard for me to muster the self-discipline to go through the steps after I've noticed my ability to stay focused has gotten so low that I should disable my browser: the steps are this: go to Settings > Screen Time > content & privacy restrictions. Toggle on the button at the top of the pane. Enter a 4-digit passcode.

There is no way for me to customize my iPad to make it easier for me to disable Safari.

This relative lack of customizability is why I would hesitate to try to rely on iPadOS for productivity. (Currently my iPad is almost entirely an entertainment and distraction device. When I need to be productive and feel that my ability to resist the temptation to waste time on it is low, I can and do move my iPad to another room.)