Are those trade deals made independently of the EU? If the EU had a hand in them, then Boris can go bugger off.
post-Brexit deal implies that this is only the UK and not the other 27 countries + the UK dealing with the USA.
What Boris is talking about is that he wants a US-UK trade deal where
1. the UK can sell British (Welsh to be specific) lamb to the USA
2. the UK can sell beef to the USA
3. the UK can sell pork pies to the USA
4. the UK can sell bell peppers
5. the USA removes restrictions on British wine (I understand the English grow a little wine now - never tried it)
6. the USA removes tariffs on UK goods (28% on fashion, 15% on machinery and 35% for food)
nearly all of the above items seem agriculture related, so American farmers may not want to allow free flow of British agricultural products.
And definitely British farmers will want protection from American products which, with economies of scale, can be cheaper.