You can use the Desktop AVD available with AndroidStudio Electric Eel canary version to test out your android apps for Chrome OS. Note that this is not available with the latest stable version Dolphin 2021.3.1.
Although, from your question, I understand you want to have a "ChromeOS virtual device". There used to be a 'Pixelbook_beta_API_25' AVD but it is not available anymore (saying this because an issue that needs to be addressed in the PixelBook emulator has been marked obsolete by the Google team). If you are not using an M1 Mac, maybe try your hand with the downloadable emulators of Pixelbook here
If you are just trying to develop an android app for ChromeOS, what I would suggest is to use the Electric Eel canary one because at the end of the day Android apps are run inside a container environment (previously called ARC - Android Runtime from Chrome). Hope this helps.