Here is an overview of all the features + screenshots: https://twitter.com/Chris_Smeder/status/1671565267145748480?...
1. Component playground
2. Redlining
3. Links to github in components
4. React mode
5. https://animaapp.com plugin will build the component for you...
6. Tasks from Jira and Linear in Figma
7. Figma in VS code
8. Autocomplete fill in code when you select a layer
FYI: To learn more about Dev mode, check out the live (free) workshop from Figma at 2pm PST https://config.figma.com/agenda?d=day-2
And here is the keynote where the announcement preview was shown https://youtube.com/watch?v=-44qrQDnLMM