Best way to manage multiple OS installations (backup, flash)

[C0ffeeFreak]

I know there are a number of threads addressing issues similar to this, but this request is specific: 

I have spent a lot of time with Mobian, and gotten it as close to my liking as possible, but I am not ready to use it as a daily driver. I would like to back up my Mobian installation and then maybe try UbPorts again. If I don't find it useable I will switch to Graphene for now.

But, in a couple months, maybe I will boot my Mobian installation again, run some updates, and see how it handles. Of course, I don't want to lose my GrapheneOS installation in case I need to switch back. 

So how to manage multiple installations? Should I just use dd?

Balena etcher, probably the program you are using to make your drives has an option to clone a drive. I haven't tried it yet on the Pine phone, but couldn't you clone the EMMC to a SD card and back again?