Wait I'm confused now, if you play a legitimate game online using a switch which has previously had a flash cart used it can be banned? I was under the impression that as long as you didn't go online it was fully undetectable, allowing you to use legitimate games online as you want without needing to switch between emummc and sysnand. Nintendo probably doesn't care about the homebrew software in the same way they do piracy, but unfortunately for them that's all the flash carts can do, hence why from their perspective I say every version is cracked.
I'm not up to date on switch modchips but last I checked you needed to solder a flex pcb such that it made contact with pads under a BGA chip. As it goes that's quite intensive rework for a hobbyist. I'm an electrical engineer and use professional BGA rework equipment at work regularly. Our success rate for BGA rework is like 80% for ICs that have been desoldered and resoldered before. Sure you don't need to remove the chip to get the flex PCB soldered, but the risk of shorting balls and needing to remove it on an expensive piece of hardware is too much for many hobbyists.