Except for Friday-Saturday is the weekend in quite a few countries especially islamic ones. Israel also has Friday-Saturday weekends to make observing the Sabbath easier. There may be other exceptions as well.

Which end?

The one at the end of the week, and not the start.

Maybe it is both ends. Like book ends.

But then surely a consecutive Saturday and Sunday would be weekends rather than a single weekend?

The concept of a weekend is a recent development that I don’t think really corresponds to what the first day of the week is (which was conceived of as Sunday for thousands of years before the weekend was invented).

When the weekend was invented, Sunday as the sabbath was still a real thing for many people. I have to wonder if originally only Saturday was conceived as the weekend, followed by the week start and sabbath of Sunday. Then, as Sunday became secularized, the weekend was extended to include Sunday.