Not the OS-included ones, afaik. Some Apple apps are through the AppStore normally, which can be updated independently (i.e. TestFlight, despite its deep hooks).
But mainly it's because base Android (AOSP) can be arbitrarily modified by the OEM; and Google doesn't want to have to trust installations of Google Play Services that have been arbitrarily modified by OEMs.
(Especially because those versions would likely all act differently-enough from one-another that they would be forced to loosen their server-side, network-traffic-fingerprint-based "authentic Android device" detection that allows them to ignore/block bots pretending to be Android devices.)
By shipping Google Play Services through the store, they can ensure that, on devices that run it, it's exactly the same code for every device that runs it, with no OEM alterations. (And they can also include various checks to reject devices that would try to alter that code at load time. This is the real reason why e.g. Huawei devices are blocked from using Google Play Services — they try to patch unspecified parts of the Play Services code while loading it, "breaking the integrity of the platform" from Google's perspective.)