Hey there! I think I have the answer for everyone in this thread. We were looking for a solution like this a while back! Viva Goals was initially fine but when Microsoft retired it we were a bit flabbergasted. 

There are some really strong options in the Teams app store but we landed on Teamflect. They are a Microsoft partner and their OKRs work really smoothly inside Teams and Copilot (also supposedly Outlook but never tried it there). The app also has performance reviews so connecting them to goals is quite useful. Anyway, if youre looking for OKRs in Teams, I can definitely recommend them. I cant speak for their engagement stuff though as we dont use those features.