You have already made my points for me. So why would the United States sign any trade agreement with the UK? You are going to either learn to pick your battles and negotiate as an "Independent" nation or learn to eat crow.Displaying a distinct lack of knowledge about reality there.
5G is not an issue, it's just the USA flexing it's muscle for economy reasons.
Iran is more complicated than the US position makes out.
Digital sales tax? Are you saying we can't levy taxes on money made by our citizens? The USA might like to consider the way it taxes it's own citizens abroad...
Agriculture? You can force substandard goods on us, but they are unlikely to be bougth by the British consumer.
NHS? Not a hope on hell. You can bid for supply contracts on the same terms as others.