I recently ordered a refurbished ThinkPad C13 Yoga (MORPHIUS) off of Amazon with the intent to modify it to run Gentoo Linux, I already know how to install Gentoo and I have read all the documentation related to my particular Chromebook, even the Hardware Maintenance Manual, so I already have a good idea how to do it, I’m just wondering if anyone else has done the same and how usuable it actually is? Thanks in advance for any advice.
I run Arch on mine so I can’t speak to the Gentoo experience, but I can tell you a bit about MORPHIUS. It runs Linux pretty well for the most part, but the embedded controller exhibits very unusual behaviour all the time, so prepare for that. If the battery dies, the laptop refuses to turn on again until I leave it plugged in for about 15 minutes. I also had an interesting adventure just the other day when I was trying to get the backlight adjustment to work properly.
I think the only other really noteworthy thing to mention is that recent versions of GRUB seem to be broken on this device. I was unable to get any Debian 12 installer to boot, and I encountered the same problem when I tried installing Debian 11 and upgrading to Debian 12. I was able to install Arch without any issues since it’s installer uses systemd-boot, which I also highly recommend installing as your bootloader, although I think it should work with anything that just loads the kernel directly as an EFISTUB.
In spite of the few quirks it has, I still really like this laptop and it’s one of my favorite Chromebooks of all time.
What kind of ec issues do you have? I’ve never seen any kind of ec issue on my morphius.
Update: got my Morphius in on the 24th, flashed coreboot onto it and installed Gentoo through the live USB without the iommu=pt boot parameter. Surprisingly the stylus, sound and touch screen worked out of the box, even the side volume keys, the only issue is the side volume keys don’t work in tablet mode, though I don’t know if that’s a me issue or a KDE issue. Otherwise it works so far, also the Gentoo wiki has an article on Morphius, but it’s incomplete. EDIT: some clarification, I’m using GRUB as my bootloader and I’m having no issues, I was also able to get ectool working, along side the backlight. I was also able to swap the drive out for an old 1TB Crucial M.2 2280 SSD, no issues with that either.
here’s the Gentoo wiki article on the ThinkPad C13: Lenovo ThinkPad C13 Yoga Chromebook (Gen 1) - Gentoo wiki
Not that surprising, hardware support in Linux is quite good. 
Most Intel Chromebooks have odd sound configurations but the drivers for those have landed upstream in the kernel recently too.
yeah, because the operating system considers them part of the keyboard, which is disabled when you’re in tablet mode.
It’s probably worth mentioning for anyone else who comes across this post that you do need to use a single-sided SSD because the connector is flush with the motherboard.
I might as well post my specs for those curious.
CPU: AMD Ryzen 5 3500C with integrated Vega 8 Graphics clocked @2.1Ghz with max boost @3.7Ghz
RAM: 8GBs of soldered on DDR4 RAM
Storage: came with a 128gb M.2 2242 SSD made by Toshiba, I replaced it with a 1TB Crucial M.2 2280 SSD, I had no issues with fitting it in the machine since it was single sided.
I suppose it’s also worth mentioning that some models of this laptop (I think Athlon CPU variants) come with 64 GB of soldered down eMMC storage so make sure you get a Ryzen version with NVMe storage if you want to upgrade the SSD.