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... (Budget: $30 - $250 USD, Jobs: .NET, App Development, C# Programming, Desktop Application, Excel, Inventory Management, Project Management, Software Development, Software Documentation, Windows Desktop)