Things I’ve found so far:
1. Audio is flakey, but it seems this has been a problem on macOS/hardware for a few years now. Occasionally during playback there will be audio popping on any tap/click (fast forwarding on youtube for example). Usually killing coreaudio D or rebooting will fix it for a week or so but it often re-appears. I think it may also be related to other audio playback software or device pairing. If you search threads this is a real thing and pretty annoying. It seems this doesn’t happen to everyone, and people suspect it is some issue with cpu load + audio playback.
2. I noticed that keyboard assembly quality can vary. When on my lap in bed and angled a lot, I can see the backlight bleeding below some keys a LOT more than others (esp caps lock). I stopped by the apple store and found that all had a little bit of bleed under keys to some extent, and maybe 1/5 like mine had a very bright glow under caps lock or under keys. No issues with functionality and not a big deal, but it does visually make the machine look not very well machined/assembled to me. (maybe can add a picture later).
I still need to test the other ports to make sure they function (HDMI, SD, headphone).
Any other hardware stuff to watch for? hinges? touchpad? other?