Send me your family history. The Boydes are as scattered as any family originating from the British Isles. There were Boydes transported to New South Wales, and others who followed as colonists. There were probably Boydes sent over to the New World before 1776 made it necessary to start penal colonies in Australia. There are certainly many Boydes in the colder parts of North America whose ancestors made their own way there looking for a better life. It isn't impossible that the German Boydes are descendants of a wandering Manxman, but just as likely that the name developed in parallel. But wouldn't it be fun to find out for sure? Tell me.
Of Celtic Origin. Most Boydes are descended from ancestors from the Isle of Man. There are branches oringinating from Ireland, and a possibly-related German clan that has been in existence for at least 250 years.
Manxmen left Man in their hundreds in the 19th Century for Great Britain to the East and North America to the West, and significant colonies of Boydes exist in Britain, Newfoundland, the Mid-West and British Colombia. There are some in Brazil, and at least one prominent family in Spain.
The Manx Boydes seem to have lived in and around the parishes of Ballaugh and Kirkmichael, on Man's west coast. Also known as Kirk Michael, or just Michael, the parish churchyard is full of Boydes, (and the largest number of Norse Crosses in Man).
There are plenty of Scottish Boydes who can trace their ancestry back to Man, or Ireland, or even Man via Ireland, but most Scottish Boyds lack something: the terminal 'e'. A sept of the Clan Stewart, the Boyds come from southwestern Scotland, Kilmarnock, a prominent anglo-norman family in the politics of northern Britain from the 1200s onwards.
It is hard to say. Linguistically, Manx Gaelic was very closely related to the now extinct forms of the language used in Antrim in Ireland to the north-west, and Galloway in Scotland to the north-east, Man's closest neighbours at 40km and 20km away respectively.
Then there are those who have just decided to spell their names that way. It is sometimes easy to forget that universal literacy is a modern phenomenon, and different standard English spellings of identical-sounding Gaelic names will have developed in different places.