So Open Source but not Free (Libre).
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…
Am I the only one that hates that programmers now have to also be lawyers?
The miniscript language itself is MIT License:
https://github.com/JoeStrout/miniscript
The Minimicro code doesn't seem to have any license in the repository or code:
https://github.com/JoeStrout/minimicro-sysdisk