iCloud backups of photos is possible without using iCloud. I use a photo syncing app on my phone that is paired with a SMB server in my home. It just dumps new photos whenever I’m on my home network. But I don’t get iCloud syncing photos to my Mac instantly.
iCloud backups of device backups requires a Mac, then setting to sync via Wi-Fi.
iCloud backups of device backups requires a Mac, then setting to sync via Wi-Fi.