Velocipede Rider on Nostr: As part of this they have locked down certain services (e.g. email verification). ...

As part of this they have locked down certain services (e.g. email verification). Thus you cannot create new Casio IDs, which explains this Reddit thread:

https://www.reddit.com/r/casio/comments/1fwg9v2/casio_id_email_not_coming_through/

That is a problem if you recent bought a new watch that has any Bluetooth syncing capability and did not already have a Casio ID because the official Casio Watches requires you to login before usage.

However, you may be able to use a third party app like "G-Shock Smart Sync" (Ivo Zivkov) which doesn't require login.