Heads-up to all the sysadmins out there: Google Calendar exports can be large, especially since you need to unzip them for importing them in a different Google workspace. The import process bugs out when the ICS file is > 1024 kb.
Luckily, I found this ICS splitter: https://brokenvectors.github.io/
Just trying to save someone a few hours of headaches.
(Yes, I know mentioning Google is possibly heresy here, please, FOSS where possible, but it's not always upto you.)