You can actually use Zstandard as your codec for 7z to get the benefits of better compression and a modern archive format! Downside is it's not a default codec so when someone else tries to open it they may be confused by it not working.
That is an interesting implementation of security through obscurity…
How does one enable this on the standard 7Zip client?
On Windows, it's easy! Unfortunately, on Linux, as far as I know, you currently have to use a non-standard client.
