Catalina partition turns into type FFFFFFF/unbootable and unmountable "disk0s2" after Mavericks install
Boot to the Catalina installer and enter the commands shown below.

Note: The values 409640 and 349609376 were taken from the output posted in the question.

gpt -f remove -i 2 disk0
gpt -f add -i 2 -b 409640 -s 349609376 -t apfs disk0