Well I suppose you are looking to have fun with your NanoVNA --- but there is likely a much easier way to directly accomplish your goal.
Many modern TV's (with digital tuners) have a diagnostic mode that will display received signal strength (along with other parameters).
So look up your model on the internet, or interrogate the internal Help File, or even check the User Manual.
Using that mode will allow direct comparison of your various antennas.
For example, many Sony TV's use something like this:
And I recall the (now decades old) Digital TV Converter boxes included the same feature.
Fred, W9KEY