Most of the time these are projects that individual engineers go through the pain of open sourcing.
They have a few products you pay for and are thus supported (for consumers YouTube Premium, Google One which is Drive storage+support, for organisations Google Cloud, Google Workspace), but for everything else, yeah. Unless you pay for One, you get no support from them on the random free stuff like Keep or Maps - you get what you pay for (in reality much more than that, something like Maps is a massive effort everyone can use for free).
The real support comes from talking with someone who works at Google and can direct you to the right team...
Yes, any of those could be defunded at any moment if it was no longer advantageous for Google to support it, but for now, they are getting support and new releases.
While I'm sure this is the sort of project that could benefit from ongoing improvements, it is also not going to decay away into utter uselessness if nobody commits to it in a week or two.
I understand the need for projects to be maintained, but I think some people have been badly burned by the Javascript world, or possibly some other language environments, and don't realize that those environments aren't the norm, but one of the extrema. Go is quite possibly on the other extrema. It does not generally decay. Again, I'm not saying that means it's totes cool to pick up a security-based project with a last commit from seven years ago and just assume it's still cutting edge, but this sort of Go code doesn't require a dozen commits a month just to tread water.