Cross-Platform Production Scheduler App

I run a combined warehousing and steel fabrication operation and I need a dedicated desktop application (MS Excel) that lets us schedule production efficiently. The tool must install and run reliably on both macOS and Windows machines and I’m aiming to have a first usable release as soon as possible.

At a minimum the scheduler should let us:
• input the difference machines and their respective production rates
• set up different production methodologies
• create and edit production jobs in a calendar or Gantt-style view
• forecast delivery and expenses depending on manpower, shift schedules, and workdays
• assign work centres, crews, or machines to each job
• track inventory or raw-material availability and usage
• produce simple status or output reports that I can export to PDF or Excel

Please outline:
1. Your proposed framework and why you prefer it.
2. How quickly you can deliver an initial working build, followed by the polished version.
3. The deliverables you’ll hand over (installers, source code, build instructions, basic user guide).

I’m ready to move fast, so if you’ve built something similar or have an off-the-shelf base you can customise, let me know and we can jump straight in.