Okay, the Azurewawe wifi card was another issue, it required a DTB patch: Using Xavier NX Dev Kit's Azurewave AW-CB375NF M.2 Module on Jetson Nano - #13 by peckama2 . After this patch, the wifi card works correctly. That is the first device that actually works correctly in my Nano’s M.2 slot. But it’s great at least one does, because this tells that the slot isn’t damaged.
The DTB patch did not help with the other two devices I’m testing, though. I’ve rebuilt kernel with PCIE_DEBUG=y to get some more information. Here are some dmesg logs:
dmesg.rj45.cable_plugging (124.9 KB)
dmesg.rj45.no_cable (80.1 KB)
dmesg.usb.1 (70.4 KB)
dmesg.usb.2 (102.0 KB)
Basically, as soon as I connect one of these devices, the Nano doesn’t even finish booting without pci=noaer kernel parameter. With it, it boots and until I start using the cards, everything looks well, but as soon as a I plug a cable in either of them, bad things start happening and it usually ends up with the Nano rebooting itself.