mkdir ~/.ssh
cd ~/.ssh
wget https://raw.githubusercontent.com/JM-Lemmi/JM-Lemmi/main/authorized_keys

/etc/ssh/sshd_config

Port 22
#Port 22222

PermitRootLogin Prohibit-Password

PasswordAuthentication no
ChallengeResponseAuthentication no

#Match Address 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16
#    PasswordAuthentication yes

from here.

/etc/ssh/sshd_config

PermitRootLogin yes

from https://linuxhandbook.com/add-ssh-public-key-to-server/

add key to root/.ssh/authorized_keys oder /home/user/.ssh/authorized_keys

Settings for only Pubkey auth:

/etc/ssh/sshd_config

PubkeyAuthentication yes
PasswordAuthentication no

password has to be explicitely disabled

Win10