Found a solution by creating a bridge which magically becomes the ZeroTier-interface.
Tested on Raspberry Pi.
# ZeroTier with IP-address early available to bind servers
# https://discuss.zerotier.com/t/bind-server-to-zerotier-assigned-ip-on-boot/25393
# 1) remove the assigned IP-address in my.zerotier.com for this host
# 2) create this file at: /etc/network/interfaces.d/br-zerotier
# 3) edit IP-address and bridge_ports accordingly
# 4) reboot or exec: sudo systemctl restart networking zerotier-one
auto br-zerotier
iface br-zerotier inet static
address 10.10.10.3
netmask 255.255.255.0
# metric 99
# mtu 2800
# dns-nameservers 10.10.10.1
# dns-search zerotier
bridge_ports ztxxxxxxx
# bridge_ports regex zt* # use a regular expression to define ports
bridge_stp off # disable Spanning Tree Protocol
bridge_waitport 0 # no delay before a port becomes available
bridge_fd 0 # no forwarding delay