We are considering adding support for TypeScript to Expo. If this is of interest, check out this GitHub issue: https://github.com/expo/expo/issues/2164. And if there’s something we’ve missed feel free to let us know.
We don’t have a timeframe on moving to TypeScript if we were to do it, but SDK 30 will be released before we make a decision. Currently we are looking to learn how interested Expo developers would be in using TypeScript, especially those who are working on Expo for business apps.