LibraryMake is not available at the time of build
If you try to install this without LibraryMake available, it fails:
~ % zef install Termbox
===> Searching for: Termbox
===> Searching for missing dependencies: LibraryMake
===> Searching for missing dependencies: Shell::Command
===> Searching for missing dependencies: File::Which
===> Building: Termbox:ver<0.0.4>:auth<cpan:JJATRIA>:api<2>
[Termbox] ===SORRY!=== Error while compiling /home/jmerelo/.zef/store/Termbox-0.0.4.tar.gz/Termbox-0.0.4/Build.pm
[Termbox] Could not find LibraryMake in:
[Termbox] file#/home/jmerelo/.zef/store/P6-LibraryMake.git/8ab4b23a981ebfd63a74c11d1398750a472195aa
[Termbox] file#/home/jmerelo/.zef/store/Shell-Command.git/59b736a276823957f655d76ff994324ea5357898
[Termbox] file#/home/jmerelo/.zef/store/perl6-file-which.git/1dfbeba2f92f8b2b04e8b26619eb20d599198d25
[Termbox] inst#/home/jmerelo/.raku
[Termbox] inst#/home/jmerelo/.rakudobrew/moar-2020.08.2/install/share/perl6/site
[Termbox] inst#/home/jmerelo/.rakudobrew/moar-2020.08.2/install/share/perl6/vendor
[Termbox] inst#/home/jmerelo/.rakudobrew/moar-2020.08.2/install/share/perl6/core
[Termbox] ap#
[Termbox] nqp#
[Termbox] perl5#
[Termbox] at /home/jmerelo/.zef/store/Termbox-0.0.4.tar.gz/Termbox-0.0.4/Build.pm:2
===> Building [FAIL]: Termbox:ver<0.0.4>:auth<cpan:JJATRIA>:api<2>
Aborting due to build failure: Termbox:ver<0.0.4>:auth<cpan:JJATRIA>:api<2> (use --force-build to override)
I'm not so totally sure about the META6.json
structure, it's the first time I've seen that.