Have they ever? ChromeOS’s original “app store” was just Chrome’s extension store. It’s been awhile since I’ve checked but Google doesn’t (or at least didn’t) officially support running android apps in ChromeOS Flex. Instead of focusing on getting more apps running on ChromeOS, they’re actively working on Google Play Games for Windows (which also hurts android). For which I think I saw that there are games that work in Google Play Games but they don’t work in ChromeOS for some reason. I’d imagine that there are a lot of other weird things but it’s been a while since I’ve actually used it.
It’s just one of those things where, ChromeOS has the potential to be a good competitor to Windows and MacOS (and maybe even a good Linux distro) but for some reason Google does nothing with it to make it worth using and actually seems to be actively harming it.