I wrote some code for a forum post that I decided against posting for (reasons). I didn't want to save it on my local machine, or off-site in Wokwi where I was testing it, and then, while I was discussing discobot on another thread, I realized I could DM myself and store forum-formatted stuff in a post where it renders as expected and is private enough.
However, the only quibble I have is that navigating back to a DM that goes only to yourself is a bit awkward-- it only seems to show up the Messages/Sent folder,
https://forum.arduino.cc/u/USERNAME/messages/sent
...not in the new messages folder, or in the notifications dropdown if you click on your upper-RHS icon.
It is an odd and likely rare use-case, so I really don't expect much support. But sorting stuff in a DM to self (or discobot) seems like a useful mechanism to store info directly on this platform.