One of the main reasons it took longer than expected to ship #signInWithMastodon is due to the max limit setting.
By default, a masto user will only be able to sign-in to 3 different Pixelfed instances.
This works by a centralized api that I run, to enforce the max limits across instances with ease.
Admins will be able to set their own max limit and opt-out of it entirely, choice is good 😉