Bryan,
The lab I worked at had spectrum analyzers and receivers that cost more than my first house. To protect the equipment our laboratory manager purchased a set of HP 11867A limiters ( I'm guessing you could buy 5 or 6 nanoVNA's for what he paid for one of those). I believe the limiter was just a couple of well matched, low capacitance, fast switching diodes packaged in a Type N adapter. It turned out that the limiters were a waste of money for our application because diodes are non-linear devices and sometimes would mix with the signal we were measuring and generate phantom signals. For tuning an antenna that extra noise might not be a concern, but for compliance testing it was a deal breaker. We eventually ordered some Type N adapter RF fuse holders that had less than a dB of loss up to 1.5 GHz. The holders had fusible links that could be replaced in-house without having to send the equipment out for expensive front end repairs. I was the beneficiary of their use more times than I care to admit.
Never tried either solution with our network analyzers as I certainly would have been fired on the spot for attempting to use an HP8753 VNA in the scenario you are envisioning. Makes you wonder what kind of front end protection expensive antenna analyzers use.
