keepassxc on more devices

I have a keepassxc database with passwords on my laptop with Lubuntu. I have a backup on flash drive via rsync. I'd like to use the same database on my Android phone and Windows machine at work as well. What is the most efficient and secure way to have a database synchronized (actual) and utilize it on all of these devices? Now, I have an idea of a cumbersome solution. To bring the flash with synchronized database every day to my work and have another copy on Android phone. What is a better solution?