Saving app-wide variable (like session) - persistence?

Can a Persistence/_Array also be used without a model? I just want to save app-wide data that’s recallable everywhere (like a session variable).
How do I get/set data into this persistence without using a model? Or is a model always needed?
If it’s necessary it’s a lot of overhead compared to sessions.

Or is the way to go with sessions and use the plugin developed by Abbadon: (any experiences if this plugin is still working as it hasn’t been updated for 12 months)?

I’m curious to hear best practice examples.
How are you solving this? Which approach is futureproof?