Like I said previously, it can be a hassle you may not even want to deal with. Take Aero for example: They have UK and ROW prices and their business is quite international, so it makes sense for them. For a charity shop to incur such a model would take quite an effort to the point it's not worthy anymore.And it’s not only the US which is causing issues with supply as on the Oxfam website it states they are currently unable to sell or ship to EU addresses, albeit not for reasons of tariffs.
Even before Brexit there were many shops that didn't sell to EU and some (like Amazon!) that would have plenty of items excluded from shipping outside UK. Brexit made it worse but within a "permanent" ruleset while the tariffs are just uncertainty, what today may be tomorrow may be not anymore.


