It’s referring to both. The recompiler links to the Zelda project and basically tells you “if you want to haven an example how to.proceed/what to implement yourself after the recompilation finished, you can use the Zelda project as an example”.

Well, usually those re-compilers or transpilers just translate the binary to some sort of intermediate language and then any backend should be able to compile it for your target system. So, in theory those handheld could be targeted. Problem with this project is that it’s not just “start transpiler, load rom, click go and your port is ready”. It’s more like "ok, here’s your game logic. Now implement the rest (or use several other projects and duct tape their libraries together to get what you want).