The iOS 16 text selection menu has a built-in unit converter:

Flutter implementation

This is very similar to the "email button" demo that I wrote with the new context menu system. If we can write something that correctly identifies convertable strings and their conversions then it should be easy to implement in the context menu.

Reference

• An article that mentions this feature:
  • https://www.macstories.net/stories/ios-16-the-macstories-review/14/#content
• Issue about all missing context menu buttons:
  • Missing default context menu buttons on each platform #107578