(I’ve had this draft sitting here for a couple months, probably should publish)
It’s concerning that the best search result looking for that mythical M1.6 screw is this thread.
I rolled the dice on the M1.6 from metricscrews.us and got them via USPS pretty quickly. Unfortunately the head is only ~4mm wide and thus doesn’t grab any of the opening at that location on the mainboard, so I’m still mainly secured using the expansion cards. On that note, the washers in that eBay grab pack look like 4mm as well.
What I ended up doing was still using screws from metricscrews.us but longer with longer 1.6 so there was room for the washer. The washer isn’t a great fit since it can slide around under the screw head, but it works better than expansion cards. I ended up using the following part numbers (note the color and material are not a match to what Framework uses, nor to eachother):
M2 Large OD Black Oxide Flat Washer #20699 (20699)
M1.6x2 Nickel Wafer Head Machine Screw #21082 (21082)
They offer the other missing screws I needed for the hinge kit and the display that are much easier to find. Unfortunately shipping cost way more than the screws themselves, which you can take as a hint for Framework’s point of view. Still, the drama is unfortunate (speaking of, I wish I could get a battery…)