There are many examples of 'skunkworks' projects, including an Asus RTX 4060 Ti with an onboard SSD slot ... The latter board included SO-DIMM (small outline dual in-line memory module) slots ...

ASUS launches its new ROG Crosshair X870E Extreme motherboard: 24-phase power, DDR5-8200 memory support, Vapor Chamber SSD ...

four SO-DIMM slots, all of which are accessible to the user. Metal covers protect them, but they’re easy to get out with just a finger. There are also four M.2 SSD slots in there, at least one ...