Swarm init+join without user interaction?

New user here, hi everybody.

Simple question: I run docker CE on devices without console or SSH. I can run scripts no problem.
I am interested in using Swarm mode.

My initial idea was to specify a shared secret to use as token, some nodes creating/managing the swarm, some other being simple workers.
But I think I’ve seen using predefined tokens isn’t possible anymore.

How would I get nodes to join a swarm without SSH/user input?

Thanks in advance!