operational device used for scanning - but what about those "other" Play Store apps?

I think it very depends on your environment.

If you have a static (maybe also isolated from internet) environment and you don't use such apps, you could still ignore them but when you use web apps etc, for example the webview app and chrome should be updated regulary for security and compatiblity reasons but always carefully.

We use managed play store for example and figured out that sometimes Google default/system apps get stuck in the managed playstore (because in the playstore there is an update available but we don't provided those to the devices) and causing an issue that provided apps are also not able to being updated.

So we decided later to update/provide all of those system apps to prevent this and since then all went fine. Even I really don't like that i need to act like that.