Recently found some clowny gist was the top result for 'google takeout multiple tgz', where it was using two bash scripts to extract all the tgz files and then merge them together. Don't do that. Use brace expansion, cat the TGZs, and extract:
$ cat takeout-20201023T123551Z-{001..011}.tgz | tar xzivf -You don't even need to use brace expansion. Globbing will order the files numerically:
$ cat takeout-20201023T123551Z-*.tgz | tar xzivf -