Ok, it's finally done. My new Mastodon account is under Fosstodon, and you may follow me there at @kzimmermann@fosstodon.org.
I initially was a little reluctant about using that instance as it has more than 13k members, and didn't want to unbalance the federation by overloading a single server. However, unlike the old Quitters, Fosstodon seems to be doing just fine and has an extensive history dating back from 2017. Also, see Mastodon.social doing just fine with 500k members.
Let the tooting begin!