Question: If deploying using the helm chart, where are user accounts and dashboards usually stored? On the clickhouse, or somewhere else?

it is stored in sqlite DB https://signoz.io/docs/operate/sqlite/

Thank you. I see the stateful set. Are there other storage responsibilities for this db aside from the two I mentioned?

Broadly anything query-service manages (there are things other than two such as saved views, alerts, channels) is stored in sqlite.