Thank you for your help
@ZachyCatGames.
I bought a 7.0 non-patched switch so I guess my best option right now is to make a nand backup, and enjoy atmosphere + NSPs (when sigpatches come) eclusively OFFline.
If emunand comes to atmosphere at some point, I'll backup my 'dirty' nand, restore the clean one, and put my dirty one as 'emu'. I can then enjoy legit online on the clean sysnand, and do my mess on emunand.
Does that sound like a reasonable plan ?