With a Vivaldi account, you can synchronize your Vivaldi browser data, participate in forum discussions, connect with people on an open social network (@YourUsername@vivaldi.net), and host a blog on Vivaldi.net (YourUsername.vivaldi.net).
Yes, as Vivaldi user you can use your Vivaldi account to enter in social.vivaldi.net, but you can also create an account direct in this instance, like in any other, without an Vivaldi account, it’s open for everyone like any other Mastodon instance. In my home timeline there are several user which are not Vivaldi users.
That’s incorrect.
social.vivaldi.net
uses your vivaldi.net account details for the account. It’s detailed on the sign up page: https://login.vivaldi.net/profile/id/signupEmphasis added.
Yes, as Vivaldi user you can use your Vivaldi account to enter in social.vivaldi.net, but you can also create an account direct in this instance, like in any other, without an Vivaldi account, it’s open for everyone like any other Mastodon instance. In my home timeline there are several user which are not Vivaldi users.