Degoo is free and has 100gb https://play.google.com/store/apps/details?id=com.degoo.android
Didn't work on s8 stock oreo. Too bad.
I use Navbar apps https://play.google.com/store/apps/details?id=pl.damianpiwowarski.navbarapps it allows custom navigation bar colors and more, no root, no pc or adb.
Edit: finally got around to going with method in OP, much better than an app, ...
Ugh, that sucks! Did you attempt to get into safe mode? I made a full smart switch backup and Samsung cloud backup to be safe, hoping if anything went Wong I could get into safe mode and restore....
There is a recovery.bat file you can run from yo...
Flip flop between nova prime beta and the new apex. Only thing I don't like about apex is that I can't figure out how to set widgets and icons to move ½ a space. Other than that, I prefer apex, it's less glitchy.