Would this work with Excel for the Mac as well or is primarily a Windows thing? Somehow, while good, I feel like Excel for Mac just isn't as good as Excel for Windows.
I wish that someone would make a Wine-style compatibility library that would run a local websocket server that communicates with a lightweight Add-In using the new cross-platform JS APIs for Excel, and translates VSTO/COM calls into IPC messages that are processed and responded to. Then you could bring all the old VSTO tools into the modern world, running in a separate process from Excel. This is... rather daunting to even think about. Arguably Apple should sponsor the project as a way to bring the world of finance towards using Macs!
Might be possible to build something that would work across all plaforms using Blazor and the Monaco editor, but that would be another huge project.