Easier, in practice. EPA reports that where radon problems have been fixed, home sales have not been blocked, and a documented system with a recent post-mitigation test answers the radon question before a buyer's inspection raises it.
More detail
What helps at the closing table is documentation. EPA advises buyers to ask for the seller's radon test results and any information about an installed system, so keep the post-mitigation test report, the closeout package, and any later retests in one place. In Ohio, a system installed by a licensee under the Ohio Radon Mitigation Standards must come with that package, including the floor-plan drawing, pre- and post-mitigation test data, warranties, and operating instructions, and the seller's disclosure form under ORC 5302.30 covers radon gas within the seller's knowledge. A buyer may still order a fresh test, particularly if yours is more than about two years old or the house has been renovated since, so a recent retest in the lowest livable level saves a step. What can work against you is a system that does not meet the standards. Ohio requires a monitor, labels on the pipe and breaker, a fan outside living space, and a discharge above the highest eave, and a licensee who services a system that does not comply must notify the owner that it does not meet the standards. In Kentucky, systems repaired or altered since 2013 must meet the state's mitigation procedures. Our radon disclosure answer covers what to share, and real estate radon services covers timing.