I got a good amount of hololive fan animation channel from this guy >>56150939

https://www.youtube.com/@komainu_JP
https://www.youtube.com/@Mochimikoo
https://www.youtube.com/@moc_neg
https://www.youtube.com/@harunoco
https://www.youtube.com/@momonofu
https://www.youtube.com/@Ebihuraii
https://www.youtube.com/@RiriZhepelton
https://www.youtube.com/@ShioPOG
https://www.youtube.com/@Tripl3jp
https://www.youtube.com/@reiruka
https://www.youtube.com/@KaraageSalmon
https://www.youtube.com/@user-cd9iu2fs5k (Nukino)
https://www.youtube.com/@user-se3bm5fj2m (Teritama)
https://www.youtube.com/@9amEN
https://www.youtube.com/@harutimu_415
https://www.youtube.com/@fuwafuwa_35
https://www.youtube.com/@user-xz8tm5ko5u (Sutorairu)

And this is all nijisanji fan animation channel that I can find

https://youtube.com/@K4N6_V1DE0
https://youtube.com/@SwooshDL
https://youtube.com/@sup3rmonst3r (can I even call this one fan animation channel? It's just has one video)
https://youtube.com/@rhaedan
https://youtube.com/@yorubi6711
https://youtube.com/@meo_135
https://youtube.com/@lookitsurei
https://youtube.com/@kurodikh__ (niji I'd exclusive channel)
https://youtube.com/@Maximuz0019

Yeah that is the only one I can find. Some of those channel have less than 10 video only the last 2 have more than 20

Feel free to adIf you know any vtuber fan animation channel that is not on the list