You are complicating issues. "Does this mean you can never visit a country EVER because of viewing internet porn?" is no if it is simply "internet porn". However, it is a hard yes in the US if it is underage porn.
If you want to go the full "I'm saying no" to everything then the chances are that a foreign country will have no access to your criminal records.
But if you are still subject to SOR/SHPO then your PPO could flag your passport if you tell them you plan to travel abroad. If you don't tell them you will be guilty of a breach. Once an order is over, then it is a lottery but not a criminal offence in the UK
People here are meant to be law abiding citizens with a criminal record. I would never suggest that people still under an order take a chance with lying. It's a moot point about what an individual can do once an offence in the UK is legally spent. I can't tell you what to do in your own personal circumstance,