After some days of opening registration on my @pixelfed server, I already have 11 active users.
22 users have registered via curated onboarding. That is: they apply for an account, need to verify their mail address (which they need to do also with open registration) and then I need to approve them.
Those 11 accounts that have been applied, but are not active, are a victim of gmail.com strict mail policy. Gmail was unhappy about the mails and refused them.
Now those accounts are in a stuck state, because they need to confirm their mail addresses before the process can proceed.
Sadly, there is no way to resend the confirmation mail from the web interface (as far as I know). @dansup is already aware of this and wants to fix that.
So, if you are waiting for your account on https://pxlfed.de/ - that's way.
In the meantime gmail.com is accepting those mails, though.