Drop-down box for a form listing all countries in the world

Hello
Is there a ready tutorial on how to do a drop-down box for a form listing all countries in the world? An additional functionality would be when entering the letter A, for example, would display all countries beginning with the letter a. Is it possible? Someone has maybe such a ready solution how can it be done?

Where to download the full list of countries from around the world?

Google it. "Json list of all countries" should get you what you need. Then you need to take the list and make it the right format for the dropdown, like

​

AUS=Australia
US=United States of America

​

so on and so forth. Then set the dropdown to "searchable" and "full text searchable" (in the options for the dropdown) and you're good to go.