Run the following commands on a new host:
  apt update && apt -y install gnupg2
  wget -O - "https://repo.saltproject.io/py3/debian/$(cat /etc/debian_version | sed 's/\..*//')/amd64/3004/SALTSTACK-GPG-KEY.pub" | apt-key add -
  echo "deb https://repo.saltproject.io/py3/debian/$(cat /etc/debian_version | sed 's/\..*//')/amd64/3004 bullseye main" > /etc/apt/sources.list.d/saltstack.list
  apt update
  mkdir -p /etc/salt/minion.d/
  echo 'ipv6: True' > /etc/salt/minion.d/ipv6.conf
  echo 'master: salt.ffm.freifunk.net' > /etc/salt/minion.d/master.conf
  apt install -y salt-minion
  salt-call --local key.finger

Init the pillar config for the new host:
<file yaml host/tld/domain/name/service/init.sls>
roles:
  gateway
[...]
</file>
Potentially include service pillar like for example:
<file yaml top.sls>
base:
[...]
  'prometheus1.aixit.off.de.ffffm.net':
    - services.cadvisor
    - services.pretix
</file>

And now check the key on the Salt Master, add the new host and run state.apply for the first time:
  salt-key -F
  salt-key -a '<hostname>'
  salt '<hostname>' test.ping
  salt '<hostname>' state.apply -l quiet --state-verbose=false saltenv=base