Install Gravity Screen and use that for screen on/off. https://play.google.com/store/apps/details?id=com.plexnor.gravityscreenofffree&hl=en
Pretty sure you could also use a button configuration app to make the volume buttons turn the screen on, and custom roms/mods let you turn off the screen via tapping the top of the screen or swiping down etc.
Also there are many Screen Off apps that let you tap an app shortcut to turn off the screen. https://play.google.com/store/apps/details?id=com.katecca.screenofflock
The only thing I can think of is Helium it's a backup app by some the the lineage guys before the rename but I'm not sure how well it's supported anymore. Might be worth a try.
Yeah computer or cloud is the way I do it. There are probably some third party app to backup things like call logs and sms too if that's what you're looking for.