I thought it would be a good idea to share this open source hardware project here: https://github.com/TobleMiner/…e-SSD-to-miniPCIe-adapter
It is a mechanical adapter that allows you to run regular M.2 NVMe SSDs inside a PC-Engines APU.
It doesn't state it on the project page, but allegedly somebody even managed to boot from NVMe. I just read that somewhere, and I'm not sure if its with unmodified official BIOS or whether a modified coreboot was needed.
I'm not sure how many people are interested in NVMe SSDs in their APU, but given the low parts/BOM cost, it might even be worth a try adding such an adapter to the PC-Engines product portfolio / shop? Doing a "reall" production run would have the advantage of proper beveled edges and hard golt plating, both of which are to expensive when doing a few one-off prototype PCBs.