I've been slowly trying to decouple myself from google in the last few years (/decades) ... but I have stuff that goes back at least 2 decades that I have been lazy / hesitant, e.g. contacts on the phone (since I doubt I would have the necessary patience to import / export / sync contacts manually anymore).
But ... seeing this kind of thing, I need to reconsider and at least keep a monthly backup or something ... as far as you know, it's not even going to be your fault when you get locked out, so you shouldn't assume it just won't happen to you.
Local backup and sync for contacts and calendar can be made using vdirsyncer. mbsync or offlineimap does the same for mail. All of them can be deployed as services to do automatic sync. Some client software can use these local copies directly.
But ... seeing this kind of thing, I need to reconsider and at least keep a monthly backup or something ... as far as you know, it's not even going to be your fault when you get locked out, so you shouldn't assume it just won't happen to you.