Settings -> auto upload. Set your options and folder mapping to the cloud. If you want it to work all the time turn off battery optimization of the next cloud app. It's been working for myself and my wife since at least 2018.
I used to do keepass through it. So yes. But I haven't done that in a hot minute. I do still have a master sync folder for some stuff... but I have tried to open any of those items on my phone in a long time.
Last I checked it worked. I haven't needed that in a long time though so that might have changed. But it's not that hard to just grab the file in the nextcloud app too.