Welcome to NT.
Sound like you have a good medical team on your side, I found therapy to rebuild cognitive function one of the most important parts of my recovery.
In addition to the vitamins make sure to get enough protein, which for some vegans can be a challenge.
Regarding non-traditional remedies, I have found meditation and gentle yoga very effective in helping with anxiety.
I'd agree with your doctor in not trying too much too soon. Your injury was just over a month ago, which may seem like a long time but it's actually very recent in TBI recovery.
Stick around and share how your recovery is progressing. Best to you on that journey.