Ideally, they're advocating for developers who are the end users of companies that build products for software development.
Their job usually involves learning about the latest product or features first, prepare learning/training content for the end users, spread the word and make more people use the product. At the same time a lot of these folks are required to gather the feedback and pass it on to their internal teams as well.
Some of them write code and build products as well, in part with any other software engineer.
They may or may not be involved in running the community around the product/company, but will be an integral part.
These roles are ideal for those who like software engineering and teaching. But there are certain developer advocate roles that doesn't need coding experience as well.
A lot of companies also try to use these roles majorly as a form of marketing solely, and are keen on having folks who already have a good social media following. So if someone says that Developer Advocates are just marketers/community managers, just run away from them.
Companies like Google, Microsoft, etc also have Developer Advocate roles but they're not focused on marketing.
Coming to folks getting remote roles, a good network really supports most of them. And a lot of companies outside India are looking forward to having more Indians use their product, hoping that they will someday turn into paying customers (individually) or use it at work (enterprise customers).
Also, college tier doesn't matter. What matters is skills, and the passion/enthusiasm. No matter how many courses or videos come on how to be a Developer Advocate (like the DSA bullshit), you may not get the job if you are unable to talk freely, especially in front of a big audience.
These roles will also never come searching for you, unless you're really active out there in developer ecosystem and has a good social media following.