Also alternative services (with their own limitations and rules) are available
that do not affect the Apple ecosystem, so could be seen as partial backup.
..And a good backup by wire to your computer with dedicated separate or
external hard drive storage, is a start of a fairly good offline library..
{I'd looked into 'google photos' but their combined services tend to try & over
control the Apple device environment; whereby they tried to make me update
to their 'chrome' browser; each time I needed my default browser, it made
me choose between Safari (recent version in iOS11.2.x) or chrome. And each
time I selected to keep Safari and not Get Chrome, I was ignored. ~ Found one
way to get control was in gmail app settings: force iPhone to use Defaults.}
..Did find by chance, images saved from iMessages (SMS + iMessage)
are also available in Mac and can be found in applications there, too..
However, it may be possible to use the free capacity of google photos for certain
archives or temporary image files. Some users suggest that images they'd trashed
or lost, were found by google photos. Not sure that's good, & I seldom use photos.
And I have other choices for digital & film photography.
