How can I come up with ideas to expand my scope on a very small team?

At a higher/abstract level, you should always take a step back to reflect what you can do to make the company more successful. What are the things you think you can contribute/lead to help improve the product, the process and the productivity of the team. In an ideal world, promotion is an after thought. Focus on learning and making the product better. Promotion will come naturally.

However, we do not live in an ideal world, so let's move onto the more tactical level. The paths to Staff engineers can vary. However staff engineers in general are expected to excel in following things

• can function as a very strong IC
• help the team to function more productively through mentorship, knowledge sharing and directional guidance.
• have org-wide impact via working on xfn initiative, being a thought leader and creating scopes for other engineers.

Based on those expectations, you can reflect upon what are the gaps in your current behavior. You should also work with managers and ask him/her to help closing those gaps.

Specifically to your question, a small pod in a startup does not prevent you from finding the path to grow to staff. On the contrary, it gives you the opportunity to demonstrate

• how you can be efficient and function well under limited resources.
• how you can lead the team to efficiently interface with other teams.
• how identify/create opportunities/scopes for you and your teammates.

To be a staff, it's no about grabbing a big project for yourself and optimize for the maximum impact possible. It's about becoming the 10x engineers that make the team, org and the company function better.

Good luck :)