I've been using CFW since CFW was a thing and I've not been banned. I've played XCI offline, NSP offline, used SX OS's emuNAND , used homebrew, booted CFW with internet still connected (not loaded homebrew though), cleared logs, updated XCI and NSP games in OFW, connected online with the switch on a lower FW than my fuses should allow and actually updated multiple times whilst on a FW I shouldn't be on and still not banned.
From what I can see, there's no confirmed bans from SX OS's emuNAND but people believe there's the potential that Nintendo could be able to tell you're using SX OS VIA the telemetry and therefore you'd get banned. I personally will only believe it when I see it happen, every single thing you do that isn't official could theoretically get you banned (except RCM, I don't believe they have the ability to log that). If you want to be really really safe I'd wait for an emuNAND implementation where the sysNAND remains untouched but it might no even be necessary, only time will tell.
The only things that I absolutely will not do because the risk is too high is: play XCI online, play NSP online and use LayeredFS.