What Excel features are absolutely essential for team collaboration workflows?

I've been developing a web-based spreadsheet application focused on real-time collaboration, and I need input from experienced Excel users about feature
priorities.

Background: I'm a software developer who's used Excel for years but primarily for personal projects. My team frequently struggled with Excel's collaboration
limitations (version conflicts, file locking, etc.), so I built a prototype web application to address these issues.

Current feature set:

• Standard formulas (SUM, VLOOKUP, INDEX/MATCH, etc.)
• Real-time collaborative editing with live cursors
• Charts that update as data changes
• CSV/XLSX import and export
• Data validation and conditional formatting
• Basic automation triggers

What I'm missing and need guidance on:

1. Pivot Tables - How critical are these for your daily workflows? Are there specific pivot table features that are deal-breakers if missing?
2. Advanced Functions - Beyond the basics, which Excel functions do you consider essential? I'm seeing requests for XLOOKUP, FILTER, dynamic arrays.
3. Macro/VBA equivalent - For automation, would JavaScript-based scripting be acceptable, or is VBA compatibility crucial?
4. Data connectivity - How important is direct connection to external data sources (SQL, APIs, etc.) versus manual import/export?

My specific question: If you had to rank Excel features by importance for team-based work, what would be your top 5 must-haves?

I've researched Excel's feature set extensively, but I want to understand real-world usage patterns from this community before prioritizing development time.

Demo available at: sheet-alpha.vercel.app (if anyone wants to test current functionality)

Looking for honest feedback about what makes Excel indispensable for your workflows. Thanks for sharing your expertise.