1/ Make the Windows version feel more like the macOS one. I switch between the two OS's all the time and it always feels jarring to open the Windows one after using the other.
2/ Add an option to cache everything locally. My phone has plenty of storage and there have been a few times where I have been with cell service or wifi and unable to pull down a document or credential I have stored there.
Mostly though I love it and can't imagine what life must have been like before password managers.