Been keeping my eye out for something like this. I have wanted to build a cheap bare metal k8s cluster for my homelab. While ARM is nice, most containers are targeted at x86.
The ODROID H2 is finally available (it hasn't been available for a long time, due to Intel not producing enough chips (or not selling them to ODROID and others, not sure)), and you can consider it a high-end SBC or a low-end NUC.
The price for board+4GB RAM is roughly 150$ vs 80$ for the RPi 4¹.
It's the lowest priced x86 system available², and the performance is significantly superior to ARM boards (in the range 2-4x of RPi 4).
¹=very rough prices; it's hard find the lowest prices, and it's not clear if it makes sense to do so
²=please no comparisons with discontinued machines (there's always somebody popping up with such comparisons...)
Edit: Do you refer to this? https://blog.cloudkernels.net/posts/rpi4-64bit-virt/
Still at least some DMA issues: https://github.com/raspberrypi/linux/issues