This is not immediate solution but a crude workaround.
On my computer I use dropbox to store the file itself. On the phone I use GDrive to open the DB file. I use https://www.multcloud.com/ to sync the folder which has the DB files 3 times a day, once at about 2 am, once at about mid day, and once at late evening.
The downside is that you need to remember that you can use only one app between syncs.