https://stepwisehq.com/blog/2023-07-17-announcing-prosemirror-net/

We've released a translation of the core ProseMirror projects to C#!

Currently we are utilizing this library in our DotNet backend to map collab edits and verify schema compliance for client submitted steps.

It's not a focus of ours, but it will be interesting to see how this might get used on platforms C# runs on natively; like IOS or Android..