[AnssiH]

I wonder what Google will do with their Cloud Platform Google-managed SSL certificates that have used Let's Encrypt so far...

But I guess in the worst case I can just buy traditional certificates for a couple of years.

[blattimwind]

You can literally exchange the certificates manually in the chain delivered by your webserver using a text editor.

[AnssiH]

There are no configuration options of any kind in Google App Engine with managed SSL security enabled (since the point is to let Google manage it), which I'd rather keep enabled if feasible to avoid having to worry about renewals etc.