Custom GeForce RTX NVLink bridges have started popping up
https://www.pcgamer.com/custom-geforce-rtx-nvlink-bridges-have-started-popping-up/
If you've decided that money is no object and, the unknown be damned, you're buying two GeForce RTX 2080 Ti or GeForce RTX 2080 graphics cards, you now have an assortment of NVLink bridges to choose from.
Whether you should actually do that or not, we can't really say until we know how these cards handle real-time ray tracing beyond the limited number of demos we've seen to date. It's an expensive gamble at the moment. Nevertheless, the hardware is available, for those who have both the inclination and requisite disposable income.