A couple of thoughts on driftwood, as I have bought, hunted, and used driftwood many times.
I have bought driftwood that was supposedly "cured" years ago. Was attached to a big piece of slate. Turned my tank water into "tea". Was a nice piece, though.
Have found driftwood, scrubbed, soaked, scrubbed, boiled, and used in tank with no issues (not practical with very large pieces).
Most recently I found a couple of pieces, scrubbed them, boiling water for about 30 minutes, then put in my oven at 200 degrees for a few hours. Afterward, I attached to rock and put in tank (obviously after I cooled off!). No issues with nasties or water coloring.