The best thing I've found so far is to export my Tinderbox document to HTML and then import / index the results in DEVONthink.
As of today, if you index the results, links between exported notes work fine on DEVONthink Mac, but not when they're synced to DTTG. That said, search works fine on DTTG, and of course you can navigate if you're familiar enough with the folder structure.
My main caveat is that I treat exported notes as ephemeral within DEVONthink. If I change a Tinderbox note's Name or Container, then the index file goes missing in DEVONthink – so I don't use DT's "copy item link", or aliases, or in general rely on notes being permanent within DEVONthink.
It is useful for taking my Tinderbox info with me at least.
Site note: I really want Tinderbox and DEVONthink to have a baby. They both do so much of what I want, neither doing all of what I want, and the friction between them causes me a lot of frustration.