4 YOE at a Service-Based Company, SQL-heavy, stuck with a 90-day notice. How do I bridge the gap to a PBC?

Hey everyone, I’ve been with my current company (an SBC) for over 4.5 yrs now. It’s my first job, and while I’ve ground my way up to being "above average" at SQL, I feel like I’m hitting a massive ceiling. I’m looking to transition into a Product-Based Company (PBC) with a target of 18-20 LPA, but I’m struggling with the "how." My Current Situation: Stack: Primarily SQL and Airflow. I’ve been on GCP for a year using Dataflow and Cloud Composer, but the use cases feel very basic—definitely not "industry standard" for high-scale environments. Self-Studying: Currently diving into PySpark on the side to round out my profile. The Big Hurdle: I have a 90-day notice period. Recruiters seem to lose interest the moment I mention it. I’m looking for some "real world" advice on a few things: GCP Depth: How do I move beyond basic pipelines? For those in PBCs, what are the specific Dataflow or Dataproc scenarios I should master to survive a technical round? (e.g., handling late-arriving data, stateful processing, or optimization).