Seems as if there are quite a variety of options, simply by typing a query into a search engine. In fact, KDE Plasma has Google account syncing in the “Online Accounts” section of settings, and it seems Dolphin (the default file manager) has native support for Google Drive in its context menus. I’ve never personally tried to use it, as I don’t associate with Google products, but it seems that it’s there natively. As far as GNOME goes, it seems at least Ubuntu (probably a GNOME thing in general) has support for connecting a Google account, but I have no idea what the experience is like as far as data syncing goes.
You don’t need a native Google made app to sync with Google Drive. Google has no interest in supporting Linux outside of its investment in ChromeOS (which is based on Linux and has Drive syncing built-in, showcasing that this is a non-issue as its main selling point). There are plenty of apps available that allow you to sync on Linux, and it seems (based on what I see in the settings pages) that there are even native options in certain desktop environments.
Maybe because there’s so many Linux implementations?
You mean distros? Linux is a kernel, and it is shared across all distros (with each distro choosing the modules and versions they support). It has nothing to do with Linux being difficult to support, or there being many different versions of it, and everything to do with the fact that Google’s only interest in supporting it is to sell a version of it with their brand on it. Supporting any distro outside of ChromeOS would be supporting open source software, which stands directly against Google’s vested interest in selling their own proprietary solutions and your user data. After all, you actually have control over your own data when you use Linux, and that’s a threat to Google’s business model.