@jcmarvillet
My advice, don't rely on a company to maintain something for us (Ubuntu Touch users).
What I would do:

manually export my calendar from google import it into a nexcloud account then sync nextcloud with UT

Nextcloud will remain and if you're using service by some company and not your own instance then don't forget to backup your data 😉

Nextcloud will be maintained as Google may decide to block any third party... They are already pushing in this direction.