Glissandi can be done on oboe with knowledge of when the breaks of a gliss happen and how to bridge those gaps. For instance, certain notes are easy to gliss between while others are not. I am including a short gliss and a longer gliss for example. Keep in mind that when you go between some notes you will need to compensate with embouchure. For more information you are welcome to check out my etude book!

Available here https://www.apakamusic.com/product/expanding-your-toolbox-a-guide-to-beginning-contemporary-techniques-for-oboe/