Yes they did!
Estonia joined the EU in 2004.
Estonia has its own currency, the Estonain Kroon, but they are a member of the EU and many vendors will accept Euros, or you can easily have tehm exchanged for local currency.
All three Baltic countries—Estonia, Latvia, and Lithuania—accept payment in euros. Estonia adopted the euro in 2011, Latvia in 2014, and Lithuania in 2015. The euro is the official currency in these countries, making transactions convenient for visitors and residents alike.
Euro is official and only currency of Slovakia after adopting it at 1st January 2009. Slovak Koruna, previous currency, is not valid since that date.
My guess, Nepal is legally accept indian currency.
Yes, Switzerland does not accept euros as a form of currency. The official currency of Switzerland is the Swiss Franc (CHF).
Not all countries along the Dalmatian coast accept euros. While Croatia adopted the euro as its official currency in January 2023, other countries in the region, such as Montenegro and Bosnia and Herzegovina, may accept euros in some tourist areas but do not use it as their official currency. It's advisable to check local currency options and exchange rates when traveling in the region.
Pound
No, they don't.
Currency gets its Power from the People who accept it. If you lose faith in the ability of the Government to stand behind a currency its value decreases, or can become ZERO. If you want to buy something from me and I refuse to accept your Currency, and demand Gold, what is the Currency's value...well Zero for this transaction.
Antigua does accept American dollars, but that is it. Antigua does not accept Euro's, Chinese currency, Indian currency, etc. before coming to Antigua you should change it all to American.
Australian Dollars ($AUD). It would be very unusual for a shop to accept other currency, perhaps tourist shops or airport shops may accept USD, EUR or GBP.