Telephone Provider ? Cellular Phones ? or Landline?

I am/was interested in an application to backup my cell phone contact list. I would like this app to back up and restore. I see little purpose in having to manually enter contacts in Nextcloud. And do not use any of the ENEMY Microsoft products. So where is this friendly phone app that gets your address book and has it available wherever Nextcloud is available.

The BLANK screen I got when I came here is like the BLANK LOOK I get when I ask someone a question they don’t know anything about… Put some content in here that says what you do.