While I found no solution using SSHelper, it is indeed possible using Termux and the Termux-API. No root is required.
After installing the Termux app, one has to install the Termux-packages openssh and termux-api:
$ pkg install openssh
$ pkg install termux-api
I also had to install the Termux-API app from Playstore or F-Droid to get it working.
The sshd ...