Looking over that guide, it’s using EXT4 as the filesystem.
BTRFS has a bit more complexity, especially under EFI and with how it’s mapped in the GPT.
Check out some hints here:
https://superuser.com/questions/607363/how-to-copy-a-btrfs-filesystem
TLDR: you need to make adjustments on some of the IDs that are pulled direct from hardware, and update those in your init as well as EFI. btrfs-clone might be the best thing to start looking into.
Elegoo petg and PLA have become my go-to over the past 2 years. Rapid vs pro tend to affect me more with how brittle the end product is than printing speed. I’m using a K2 Plus, but also printed on Anker M5C.
Fun detail: you can order 10kg packs for a good discount vs other shops if you hit their site directly.
My only gripe is they don’t have variety packs of their fancier stuff. Some of their silk is gorgeous.
I usually have gotten about 35-40% rh on my should out of the bag. I still get good quality at that level, but would warn to actively dry a bit if you are in a more humid area for sure.