That's usually called "source available", since most people, including some governmental orgs around the world, already follow OSI's definition for "open source".

For miniscript: the Free Software Foundation considers the MIT license (which they call the ‘Expat License’ to distinguish it from the ‘X11 License’) to be ‘free’ (and GPL compatible), but not ‘copyleft’.

https://www.gnu.org/licenses/license-list.html#Expat

For minimicro-sysdisk: I am suspicious that the author just forgot to include a license. Their other repos are mostly MIT or ‘The Unlicensed (also ‘free’ but not ‘copyleft’), and some have licenses added after creation. Suspicion is not something to be legally relied on of course…