EF supports INNER JOIN, LEFT and RIGHT JOIN, and can produce self and cross joins. However, it currently cannot produce a FULL OUTER JOIN, as the LINQ operator for that is missing.

This is notably needed for scenarios like hybrid search, where two search resultsets (full-text search + vector similarity search) need to be joined and ranked together (via e.g. RRF); in this kind of scenario, highly-ranking results from either side should be included even if there's no result on the other side. See this blog post for example usage with SQL Server.