The best friend I've made as an adult was met through work. Then he took another job, and I moved across the country when I went remote. We still keep in touch and occasionally travel to visit each other.
Most work “friendships” are transactional. Always exceptions of course, like in your case, but it’s important to be clear eyed going in.
A lot of people in my life have had their feelings hurt when their “work friend” stopped talking to them after leaving the company, because they failed to understand this important truth.
The kind of person who can't make and keep friends unless they are forced to work in the same office won't. It that person could keeping touch and would pick friends able to keep in touch, they would keep.in touch with whoever they studied with or was in their hometown.
But, we are talking about someone who need coercion to make friends. And they can be nice super ethical person, but there is that skill they don't have.
At any point in life I keep in touch regularly with about 40-50 people.
Most of them are from outside work. Because "but you spend 8 hours with them every day" is not true for most people. I now work with completely different people than I those I worked 3-4-10 years ago. I have friendships significantly longer than that, and I didn't have to work with them side by side all this time.
The best friend I've made as an adult was met through work. Then he took another job, and I moved across the country when I went remote. We still keep in touch and occasionally travel to visit each other.