Thank you, all, for your responses.
For the time being, I accept that Dropbox is the only game in town, and that 2MB is available at no charge.
I want to be able to send a copy of a RM database to people with an iOS device, who are not close enough to me to make travel a realistic alternative. I would like to have the database be stored on their iOS device, since there might be circumstances when they might be reluctant to access the internet in non-secure places, and therefore not have access to Dropbox. What would be the solution. As I understand it, the iOS based RM cannot 'save' the database to local storage in the iOS device. I have looked at and tried the new iOS 'Files' app, but have not seen where the RM app stores its on-device databases.
In addition, when using the new 'Files' app, I can see that it has access to such storage apps as OneDrive, iDrive, Box and of course Dropbox. I would like to see the RM storage space be opened to this storage app. Can this happen?