How do I backup to my ipad and not use icloud

You can plug our iPad into a computer and back up to that - no icloud required.

Back up iPad - Apple Support

I have used google to back up my photos and docs, but for normal use, you have to use icloud. There are dongles you can use with memory cards, but at some point your ipad will be full, because of updates.

Not true; see the link to Apple's instructions.

And, a device will not fill up from updates. It will most likely fill up because of all the videos, photos, and movies you downloaded. Keep an eye on that and you can easily manage the space you have.