Well the AMLG12B build is a stripped down & optimized AMLGX build. So technically all AMLGX builds will run on S922X/A311D boards to. It only builds the panfrost Mesa driver & GCC optimized the build for big.little A73.A53 cores.
But the main problem is that the AXG (iirc) audio driver is faulty, Lima does not run Qt stuff (at least it did not start when I did some sort tests) and my s905X board tends to try to fry my speakers by creating randomly static blasts & noise.
Beside that the video decoders are still unfinished and so there is no use as a daily driver at all.
So if you want to tinker a bit feel free to build images yourself, they should compile fine but offering them as download doesn't make sense from my perspective. Whoever fix something... PR welcome.
The AMLG12B builds however have way fewer audio problems and since the SoC outclasses the competition it's worth to offer builds for the N2+ / Vim3. However the video decoder still are incomplete & the panfrost driver is not as fast as libmali.