I installed Debian Jessie to 32 GB eMMC, but it's not working. It works for some time but then I start getting a lot of I/O errors, so much that system eventually remounts everything as read-only (which is why I can't save these logs as text and have to take images). Is eMMC faulty or what is going on here?
You don't have many options. If it's an empty system, install a different distro and run a diagnostic tool. If the errors persist, you most likely have a faulty eMMC.
Since Debian Jessie is quite old I decided to test also with Stretch RC-3, and so far I havn't seen any problems. It's possible that this is a kernel bug in Jessie. (But I'll test more tomorrow - for now I'm just watching some cute YouTube videos.)
Seems like you've got it going but a few things come to mind in case you need to revisit this. Have you tried Windows? I don't necessarily say that it's more reliable but maybe the drivers are better? Would a USB-based diagnostic tool work? 'hdparm' is available on some live Linux distributions. Maybe that'll help. I need to verify that *my* eMMC is working!