Slayers: Volume 1 by Hajime Kanzaka is now available as a DRM-free mp3 audiobook on Downpour.com
https://www.downpour.com/slayers-volume-1?sp=794225
The publisher is listed as "Findaway World". I did some searches for that publisher and "light novel" and "Young Adult Fiction" and found some more audiobook light novels by J-Novel Club and Seven Seas. Findaway publishes other audiobooks too.
Some of the lightnovels.
Reborn to Master the Blade: From Hero-King to Extraordinary Squire: Volume 1 by Hayaken
https://www.downpour.com/catalog/product/view/id/832611/s/reborn-to-master-the-blade/?sp=832612
The Saint's Magic Power is Omnipotent (Light Novel) Vol. 1 by Yuka Tachibana
https://www.downpour.com/the-saint-s-magic-power-is-omnipotent-light-novel-vol-1?sp=796306
Yen Audio titles are also available on Downpour.com
https://www.downpour.com/catalogsearch/result/?q=yen audio#q=yen audio&idx=live_downpour_en_en_products&p=0&dFR[imprint][0]=Yen Audio&is_v=1
Including:
The Miracles of the Namiya General Store by Keigo Higashino
https://www.downpour.com/the-miracles-of-the-namiya-general-store?sp=730497
Not a light novel, but a time-travel letter-writing mystery.
I've Been Killing Slimes for 300 Years and Maxed Out My Level, Vol. 1 by Kisetsu Morita,
release scheduled for February
https://www.downpour.com/catalog/product/view/id/873529/s/i-ve-been-killing-slimes-for-300-years-and-maxed-out-my-level-vol-1/?sp=873530