An dropdown entry with 300 choices can be as hard to use as this browser's built-in date input - if I want to enter a date before 1970 or so the years and months scroll past so fast it's an exercise in dexterity and most times when i let go the date isn't updated!

To get round this for countries you can usually type the first letter or two, although that's not going to work so well for Chinese...

A list that has recent values and one's current location (and maybe, if known, one's home country) duplicated at the top, as some word processors do for a fonts list, would be workable.

BUT input type=country with autocomplate but where the user can override the value, and falls back to a plain text field, seems to get around a lot of the problems.