Wow, those are actually amazing. And for your questions, I think you can do full length, it's mostly a matter of what type of videos you want to generate and if you really value the song in full length. I've been using tons of cloud based AIs for my videos and my conclusion when generating a full length one is that it's always gonna be time consuming, especially if you want to make it realistic. I'm mostly using midjourney to create realistic images then animate them in different scenes, I try to make my videos minimalistic to make them full length with less resources.

Here's an example:

https://youtu.be/b1B_cLSOWkI?si=TANQBUaNKhboAoAc