This is for very low resolution only and AI up-scaling then takes another long time. Yes SD can work with 8gb vRAM and 12 is nicer, but the upcoming SDXL will probably require 16gb to work good enough.
I agree that Nvidia is crap and would love to recommend AMD, but their software for AI stuff is just bad right now and their business decisions to only support the newest data-center GPUs with it is even worse.
I have an all AMD Linux system, and it works great for gaming and VR, but I have given up on trying to get SD to work on it despite spending a lot of time on that already. Maybe with a newer card it would be better, but I think the risk is just too high to spend a lot of money on an officially unsupported card that AMD can break any minute and has done so in the past.