The documentation for all three of Silverblue, Kinoite, and Sway Atomic have the same phrasing “With Fedora , only certain mounts can be manually specified as partitions. These include:…”
The use of the word “include” implies that this is not an exhaustive list, but I cannot find any reference to other supported mounts.
If others are supported, what are they? If no others are, then could the phrasing be changed to make that clear?
I think the subdirectories under /var is where they do not get exhaustive with the list, and I imagine you could also make one of your own as well (e.g. /var/data, /var/backups, etc).
Welcome to the community!
Added docs-team
Welcome to 
The Docs need to be updated. . . Which is a recurring theme here.
Can @siosm @boredsquirrel Give me a hand here. I have mounts of my own when I do Silverblue activity, but what are the “Good practice, Supported” mount points for an OSTree install ?
Added atomic-desktops, filesystem, mount and removed kinoite, silverblue, sway-atomic
With Fedora Kinoite, only certain mounts can be manually specified as partitions. These include:
- /boot
- /var
- Subdirectories under /var, including:
- /var/home (Fedora Kinoite has a symlink from /home to /var/home)
- /var/log
- /var/containers
- The root filesystem: /
I agree the first “include” is not correct.
On an installed system if you use ls / you see a lot more, but nearly all of these seemingly writable directories are links:
The wording here is correct and the first one can be removed. You are welcome to open a PR on the docs page.
I never know how to interpret that emoji
Exactly ! 
Mostly what’s in the docs right now.
The list is not exhaustive because anyone can mount anything inside the mount points listed. The main one is /var, where you can create any folder and mount anything you want.