1. NextCloud started off as a web-based solution, but can use APIs and WebDAV to allow connections NOT from only a web site. Accessing documents and media are where it excels at. Choosing where to sync it is up to you.
2. Backing up. NextCloud is my phone backup (and my family's phones' backups) in terms of pictures and videos we take with the cameras. It goes to a server that has redundancy (RAID), and then 2 external HDDs I switch out on a daily basis, keeping one off site. If I trusted the cloud more, I could also tell NextCloud to backup to Google Drive, AWS, etc - but as a Canadian, we…