For secrets, I personally use Github for that and you can add them in as a build step. Google also offers this: https://cloud.google.com/functions/docs/configuring/secrets
For logging, I just use Google's logging layer. If I was to migrate somewhere else, I'd just use that logging layer.
For releases, I just used github releases as part of my build step. But google also has the concept of releases... https://cloud.google.com/functions/docs/deploy
and on and on...
None of these are major lock-in problems though... any other PaaS platform you want to go to will need those sorts of things too.
My point is that this is the solution to use and there really isn't any reason to switch. But, if you really were that bothered that you wanted to to switch, you aren't super tied to it in your codebase. I'm not saying the cost to switch is zero, I'm saying it isn't impossible.
