How to use onedrive or other cloud services as a backup target for iPad and iPhone?

When the iCloud storage reaches the very old level of 5 gigabytes of data, backing up of the devices stops and you are required to buy additional iCloud data to safeguard your data and the backups of the devices.

The software defaults to iCloud as the default backup target. Google Drive, (1TB) OneDrive business or a European cloud/storage (GDPR approved) provider cannot be selected.

Isn’t this a monopolistic practice?

Also 5 gigabytes are quickly filled with the ever expanding iOS / iPadOS features, increased on-device memory and increasingly better cameras filling up space even faster. Now the iPad and iPhone use different operating systems, the backup size grows faster and faster.

Requesting a way to select a preferred cloud provider for backing up iOS/ iPadOS devices.