How to attach files other than iClould?

What I did: I want to add files from other places such as Dropbox or google drive

What happened: could not find possibility to do so in the attach files menu

What I expected: is there any way around?

Things that might be helpful to know (Agenda version, OS and model, etc):

On iOS/iPadOS, you can usually go into the app (eg Dropbox), and choose the action button (box with arrow icon) to share a file with another app. You should then be able to select Agenda.

Some apps also should integrate with the Files app of Apple. I think if you then click our + button to insert a file, you should see Dropbox in there, together with iCloud. You might have to search around to find it.

Kind regards,