You can already hack this by defining access policies and writing an EdgeQL proxy server that authenticates incoming requests, sets the appropriate global, and forwards the query to the database. There's a Python/Flask implementation of this pattern here[0].
We also have a JavaScript example app demonstrating access policies to simplify authorization logic using Next.js/getServerSideProps[1] and a user management platform you may have heard of called Clerk[2] :)
[0] https://github.com/edgedb/edgedb-examples/tree/main/flask-pr...
[1] https://github.com/edgedb/edgedb-examples/blob/main/nextjs-a...
We'll be working on tightening and adding the necessary security mechanisms to allow exposing the DB directly to web in 3.0 and onward.