RelativeArea0
Its mostly safe if you compiled it from revanced.app or from github.com/revanced
As for account bans, I've been using it after vanced died and my accounts (including that has purchases) wasn't banned so maybe its a regional thing(?), I can't 100% tell.
PS: if you decided to give it a try and use your accounts, make sure to use the "vanced" version of microg, idk why but vanilla microg doesnt work with revanced in my experience
Steel wool and a water bucket or running water
"Disposable" electronics
Yep, too overly specific or weird on some stuff, like for example on installing packages via terminal, I just went with suggesting it because I haven't fully red and understood your query, my bad :)
As for auditing tools, I can't think of any because there is a lot of ways how to check logs and it is messy ngl. If I'll be honest with you how I kinda survived linux is by automating backup of important files through nas and if I f*cked up my system, instead of fiddling the logs to find what went wrong, I'll just nuke it.
Opensuse has GUI frontend that controls almost all the system settings called YaST, why dont you give it a try
everything has trackers, even those APs or wifi routers flashed with 3rd party firmware (openwrt, ddwrt, etc). If OP is willing to spend time on doing packet tracing or even the most simple one like a setting up a localized dns server/sinkhole, OP might be amazed what lights up.