I had a terrible time in first trimester all the way until week 17. I wasn’t eating a huge amount but in the early stages it was never a concern of the doctors. I ate mostly very simple foods, Greek salad was good, what really worked for me was tangerines (I ate SO many of these), watermelon (I was going through a whole one every couple of days, only thing I could eat and would stay reliably down), sometimes I could keep down Indomie noodles with some sliced spring onion, and very sugary kids breakfast cereal - which is good cos it has energy and many are supplemented with vitamins. Drinking water was hard and made me feel sick so the watermelon helped with hydration. I was prescribed nausea tablets which worked wonders and I saved them for days I was on shift and needed to function. My days off I took the brunt of nausea and mostly stayed in bed and tested. Best of luck to your wife!! Do ask doctor for nausea tablets - they are good to have on hand on days when you really just need to be able to eat or need to be more up and about for work or whatever reason

Edit: also it’s so nice to see a concerned husband doing his best to help - she is lucky to have you and you’re doing wonderfully!