I don't have 100% solution, but just a theory below:
Once you get that email, they will mention that the physical address can be different from︂ the registered company address, etc. Including co working spaces. It does not sound very complicated︃ to get a real physical address of a place where you work, so you can︄ just go to a random co working space and rent it for 1 month and︅ get some kind of proof from them. Maybe a small trip to nearby country that︆ has trading address option on wise. I honestly think there will be no documents asked︇ at all.
When you get that option to add the trading address, you just fill︈ 4 fields, country, city, address, post code, and click save. There is no other page︉ requesting docs, you can also delete/edit this address anytime you want, you can also add︊ multiple trading addresses, I don't know the limit but I just added 1.
The only︋ address that is uneditable is the registered company address.
I also saw on other forums︌ where people from certain countries also had no option to add their country as trading︍ address but they managed to fix it by phone call, all they did was called︎ the customer support and told them to add an address that was not in the️ option list.
Anyways, I will update this thread once I get any updates from wise for my situation, if they even request docs or all went smoothly.