Velopack works great for my standalone app ! Thank you !
I would like to use it for updating just a plugin dll hosted in a bigger process (Revit).
On Discord @caesay sugested this might not work.
I would do it like this:

1. The installer puts my dlls and an exe to %appdata% as usual.
2. After installation, the exe runs. It does not have any UI. The exe has the .WithFirstRun hook and finds out if Revit is present and registers the location of the dlls with Revit by putting a xml file in a plugin folder. This is the only time the exe actually runs any code.
3. When the hosting app Revit launches my plugin dlls (from the appdata folder) it checks for updates via updateManager.CheckForUpdatesAsync() and does updateManager.DownloadUpdatesAsync(updateInfo)
4. When the main hosting app shuts down the handler of ApplicationClosing Event triggers .WaitExitThenApplyUpdates(...) .
5. Next time the host starts (manually) the update will be there.

Would this work?