Using LineageOS native SSHD over ADB
AFAIK with LineageOS 14.1 (I have a rooted FairPhone 2), sshd is enabled by default and ready to use. Its config file is /system/etc/ssh/sshd_config which points to /data/ssh/ for keys storage. I guess you can reconfigure it to use /sdcard/. In theory, /data should be preserved across system updates, though I have not much experience to confirm it. The daemon needs to be started manually (this also generates the server's key pair; note that the start-ssh doesn't launch sshd in the background, hence the &amp;):

$ adb root
phone # /system/bin/start-ssh &amp; 


Alternatively, you might want to configure another sshd instance as explained here. 

To have sshd start at each boot (I still haven't tried), one option is to use Termux:Boot. Be aware that having a daemon always running might drain your battery!

As for running ADB and SSH, you say 


  ADB allows forwarding from local host:XXXX to the phone on port 22


It is my understanding that this is not correct (unless you mean forwarding from a dev machine to another host which the phone is tethered to), as I don't see how adbd can handle encrypted connections. A quick sniff test with ngrep shows that my Wi-Fi connection on port 5555 is clear text.

Otherwise, make sure (I guess you already know it, but repetita iuvant...) that on your phone


Developer options are enabled
Developer options -&gt; Root access is set to "ADB" or "Apps ADB"
Developer options -&gt; ADB over network is enabled


Then, on your computer terminal, the following command should get you on the go:

$ adb connect &lt;your-android-host-name&gt;
$ adb shell


...expect an excruciatingly slow, not encrypted connection :-(