DT3P (kind of) crashes when opening an encrypted DB

Then yes, a local sync store on the SSD would be a nice option IMHO.

So, if I’m not able to use local to sync to DTTG, can I connect my ipad to a terminal via lightning cable in order to sync it? I read somewhere this is possible.

This would be a Bonjour sync, and yes you should be able to do this.
There is a forum post specifically about Bonjour: Bonjour Simplified

Also, don’t forget Sync is covered in the Help for each application:

  • For DEVONthink, sync is covered in the Help > Documentation > In & Out > Sync, Preferences > Sync, and Troubleshooting > Sync Issues.
  • For DEVONthink To Go, sync is covered in the ? > Help > Sync your databases section.

There are also manuals available here: Manuals