Neon's free tier limits compute hours and storage, not the number of queries or dashboards you can run. So building a dashboard on top of a free-tier Neon project works fine for light to moderate use.
The thing to watch is autoscaling and compute suspend. Neon can scale compute down to zero when idle, so the first dashboard query after a period of inactivity may be slower while the database wakes up. A reporting tool like Draxlr connects directly to Neon's serverless Postgres, so your dashboards always reflect current data even as compute scales up and down.
If your dashboards get heavy traffic or need to stay consistently fast, you may outgrow the free tier's compute allowance before you outgrow anything related to dashboarding itself.