I will reiterate my chief complaint with this: it should have just copied the VSCode extensions API from day one and relied on easier porting of them.
- committing to implementing every new documented Code API function as quickly, completely, and transparently as possible, because if you don't, extensions will break;
- resolving mismatches between how Electron apps do things and how AppKit apps do things, which may be easier said than done;
- possibly choosing not to support functionality in extensions that Code doesn't have;
- putting control of your flagship product in someone else's hands.
So I'm not really surprised Panic hasn't done that. If there were a way to create a basic converter that takes a Code extension as input and spits out a likely-needs-work Nova extension, kind of like there's a converter for TextMate syntax definition files to Code's format, that would be great, although that would almost certainly be easier said than done.