There is a slight chance that the rim has been bent by the impact, but I think that would be pretty unlikely to happen unless you hit something hard enough to flatten the tire as well. This could probably be confirmed by seeing if the spot where the rim comes closest to the brake pad on one side is closer or farther at the other side at the same point. If both sides are closer, you may have bent the rim, if one is closer and the other moves farther, it is probably a truing issue.

Assuming the rim has not been bent, the wheel could be trued, but if it doesn't rub the brakes when riding, it is fine to ride it the way it is.

If the wobble is only about 1mm, I would actually wonder if hitting the branch did nothing, since a perfectly true wheel is pretty rare.

I have had wheels so out of true that I had to adjust the brakes outward to keep them from rubbing, and the wheels lasted for a long time that way, so you aren't looking at anything super critical.