Migration paths for non-mods are limited, unfortunately. The list can be added to, on non-beta sites (but still not easily -- there tends to be some politics involved, I think). I.e., it is meta or bust for us.
Mods get to send stuff wherever they like, of course. :D At least until the nice men in white coats show up. I am currently fixated on finding a question I can straight facedly migrate to Worldbuilding.
In all seriousness, part of the contentiousness and restrictions around migration paths has to do with the predilection/temptation to use it on very low quality off-topic questions (aka. "migrating garbage"). Blatantly off-topic questions seem to often have quality issues.
On the one hand, it could be said that the quality is besides the point and can be addressed on the other end. On the other, this probably doesn't do anyone any favours. There is also a technical issue in that if a question is migrated then closed because of quality, the system deals with this as "migration rejected".
I tend to close as off-topic more than I migrate. This hopefully alerts the OP to the fact that there are standards and expectations, and gives them the chance to have a look at the recommended site (if any) before posting again.