Hi, my name is Ivan and I am a developer of the Photopea photo editor, which works in a browser and has an excellent support for the PSD format.
Now, I have added the support for Sketch files. You can open any Sketch file, view the file structure, edit texts, export as PNG etc. Since Photopea can save documents as PSD, you can use it as a Sketch to PSD converter.
Instead of writing the details and how everything works, take a look at several examples. Also, feel free to try out your own Sketch files :)
Do you think it can be useful for you? If yes, what other features would you like to have? :)