If you still choose VPN, forget openvpn, then you probably should take a look at wireguard.
Can you offer a guide, plugin for end users?
Yes, when I find some time I will. PPanel as guide could be done too I guess. Good news it will be implemented soon.
For ssh it is even better not to set a password
I fully agree, as passwords can be cracked whatever length they are. If you install as example ubuntu/debian server, if you set password for root user (you can leave it blank), then your root user will be with admin privileges, if you do not set root password, then your user will be added to sudo (in Debian, if you set root pass, user is not added to sudoers group).
All that makes sense, root is bad because you do not need to guess the username and that is why it is best if root has no password at all (even account). However, for some who read, please do not think you should not set your root password on receiver because in enigma2 it is designed to work as "root". In enigma2 you still can do whatever you are able to do in linux, like creating own/new groups where you add your users and restrict them also in WebIf etc... .
If you use your ssh key for services (like autossh), you should not set a password because service can't type it. For setting own user key for usage with manual interaction, password can be set. Good example for that are company PC's, you never know when your admins go rogue and copy your SSH keys (just one example). On private PC's, it differs by user requirements. In general, better use disk encryption which would prevent a thief access your data, possibility that it is stolen over internet from your linux pc is quite minimal.
Many people who want to use it for streaming and create RSA4096 keys will probably not be able to stream as encryption is too high for most receivers, RSA1024 would be alredy much faster but less secure. With SSH you can make it easy, you create hig and min security keys, lets say http/https/ftp/ssh ports use highest security second connection with RSA1024 for accessing stream ports. With openvpn or other solutions mostly gateway and routes are automaticly configured, you can do so manually but it is problematic to have multiple VPN connections on same interface, where you are not restricted in amount of SSH tunnels which you also can setup over VPN's (or VPN's over SSH).
Wireguard is faster than openconnect and I can stream 4k raw streams over openconnect, would have to try it with SSH, but sf8008's cpu is not that powerfull I guess to stream 4k over rsa4096 encrypted tunnel, will maybe try next week when I got time.
In my short advice about autossh above is one typo, -D PORT -p PORT should not be placed after the hostname but before, will edit it now.