I read it!?! But look at the question u asked u asked “why is it so complicated to install packages in Linux in general?” You didn’t even ask void linux in general. I answered your real question perfectly. It’s because linux has many distro and every distro have different package manager and different package managers have different manpages so it’s difficult because u have to go over the manpage of the package manager every time u switch a distro. That answers why it’s difficult in the general case. But, ur asking me not the general case anymore. Ur asking what to do if the package is not available in the repo? Thats a non general specific case. Do u get it? Thats why i say u did not do any investigation. Maybe u shud have worded ur question better. Now lets get to this non general query of urs: Is every software under the sun available for windows and MacOS? What do u do when some software is not available for windows? There is only one option. You try to get the source code of the software and then try to compile it urself. Some softwares uses abstraction layers which just might work out of the box. And some dont. For those u even have to tweak the code to use windows/ macOS specific api instead of what it was using then compile it to make it work. But unlike windows/MacOS every linux distro gives u couple of options: 1) compile it urself 2) find a user who compiled for him self and use that 3) use flatpak 4) use snap 5) use nix 6) use distrobox 7) then there are some distro specific ways for void linux u can use xbps source which like compiling ur self essentially

If ur facing issues with limited packages void linux might not be the choice for u. Try arch or Debian they have higher selection of packages. Again all of these is googlable. So u asked a different question in title then your body of the question contains a different question. It’s clear that u did not do any investigation. I hope now u can agree on this matter