I am very pleasantly surprised with the most current release of the iOS Bullet Journal application. It is in no way designed to take the place of your paper journal. But allows you to photo your pages and assign them to a calendar day and page number inside of a journal. Another nice feature is the ability to assign a page to a Collection.
Most importantly, it backs up to the iOS Files application. I can use my iCloud Drive to store the backup file. No new account is required. No new subscription is needed.
The application fully supports the Bullet Journal methodology, but gives you a way to review your notes even if you are away from the physical copy.
Lastly, in a pinch, there is an ephemeral 72-hour Log for Tasks, Notes and Events. This provides a way to continue to capture until you can return to your paper Journal.