You might want to confirm that it is indeed zypper packages before you rearrange too much: Disk Usage Analysis on the desktop, or du -sch * on the console will get you some numbers by directory. It could also be cached packages, clean them up with zypper clean --all.
I’m not sure about specifying different destination directories with zypper, but you could try installing something like vscode from Flatpak rather than zypper, and specifying --user so it goes into your home directory (if that’s a different partition).
I’d also look at your containers with podman and clean up any old ones, they can take up a lot of space.
Nice. I’d not thought of that one.
Yes, std::remove_cvref_t combines the other two, in fact I believe it does so precisely (see the “Possible Implementation” on cppreference.com). The “…with a little extra” that I mention for std::decay_t in the article is that it does the same as std::remove_cvref_t plus some standardization of array and function types to pointer types (again, see the “Possible implementation” of it on cppreference.com). For my purposes it doesn’t really matter which to use, and I mostly prefer std::decay_t for its brevity.