Well ok, your premise is that the dollar value drop of GBP was good because it causes Americans to buy UK made products.
You can devalue your currency without leaving the EU, you just print more of it.
China does this all the time and it's one reason why they have become the manufacturing capital of the world.

When a country does this, it harms the people who hold rely on that currency to feed themselves and their families and strictly favors the businesses that are doing foreign trade. It mostly harms businesses that are bringing local products to a local market. Although it can help them in the long term, because this does make foreign imports a tad more expensive.

China softens the blow to their citizens, by having an internal and an external currency. The external currency when devalued does not flood the local market. It is instead sent to the US where they buy "future dollars" via the process of holding treasury bonds. This is where we get the myth, that we owe some debt to China we can never repay.

Sure we can, we just issue Tbills with a negative interest rate, and convert existing bonds at maturity.
Yes there will be less dollars, but each one will be far more valuable.
This undoes some of the damage to our own economy that the we have allowed the chinese to do to us by devaluing their currency, while still technically having a "preferred trading partner" status, despite china buying essentially no US made goods.

We can only do that while the US Dollar remains the world's reserve currency though.