You don't have to use iCloud. You can use local storage, or any cloud provider, or SMB/CIFS.

would also be nice if webdav could just be mounted. i mean caldav and carddav are supported in base os, whats the problem?

I don't know about WebDAV but it does let you mount SMB shares.

If you need WebDAV I think Documents by Readdle will do it, and maybe even makes the share available to other apps though its File Provider. But I'm not sure what parts of Documents are subscription based now since I have a paid copy from before it went subscription.

It even has the option to keep a local copy of folders from network shares so you can use them offline, which is a pretty handy feature if you're working with large files or don't have a cellular iPad.

i'm using documents in free mode for some time, might be worth it if it can really transparently make webdav available to other apps.

I recall it being supported up until iOS 14 or 15 too, for some reason they just decided to remove it.

You don't need iCloud, in the Files app you explicitly have "iCloud Drive" and "On My <device_type>" as top-level root directories to save files, you can maintain everything local as you wish...