Project Management App in Google Sheets

I need a streamlined project-management application built directly on Google Sheets, tailored for construction and engineering work. The data already lives in several spreadsheets; your job is to turn it into a single, reliable workspace that supports multiple user roles and keeps every stage of the job moving without email chains or manual updates.

Core deliverables
• Dashboard – an at-a-glance view of project status, budget burn, pending tasks, and critical dates, driven by dynamic charts and conditional formatting.
• Workflow automation – Google Apps Script routines that create tasks, nudge assignees, escalate overdue items, and stamp time-stamped history records automatically.
• Approval system – tiered sign-off (site engineer → project manager → finance) with locked fields after each approval level to guarantee data integrity.

Access must be role-based so that site teams see only their tasks, managers see portfolio metrics, and admins retain full edit rights. The solution has to stay 100 % inside the Google Workspace stack, so please leverage Sheets formulas, Apps Script, and—if it speeds delivery—AppSheet views that sit on top of the same sheet.

Hand-off is complete when I can:
1. Add a new project in under two minutes.
2. Watch tasks cascade through the approval chain automatically.
3. Export or print a Bill of Quantities summary straight from the dashboard.

If you have previous examples of Google-Sheets-driven dashboards or automated approval flows, that will help me gauge the fit.