There are several companies working on PCIe slot SSD adaptor cards that would allow you to get gen5 speeds on your z690 board, but you'd have to lose the GPU or run both slots in x8 mode. Depending on the card, that may be totally fine for you, but it all depends on what you're doing. Also, when I looked a couple weeks ago for someone else on the forums here, I couldn't find any of those adapter cards for sale yet. Several have been announced over the last few months, so I would think they'll be on the market soon.