So, I use a file manager app called “Solid Explorer”. I can set up most popular cloud drive, my website’s FTP server, an SMB network share in my house, whatever, as a storage item, and after that, I can just copy to any one of those like I’m copying to another folder inside the app. Much prefer that to using the individual apps. You can WebDAV to Nextcloud that is self hosted, too.

If you have a web host, depending on your contract/plan, you can run nextcloud there on your webserver space, and access it from wherever. This avoids the dangers of possibly opening up your home network to outside world dangers. Just make sure your hosting plan includes enough space/bandwidth to suit your needs.

> self-hosted nextcloud?

I chose dropbox as it’s the only option that will work as a webhost for my calibre library

Using pCloud and is very satisfied. One can buy life-time storage if one prefers that over subscriptions, and it seems to be on sale almost all the time