Is it not possible to lock the course so i can fly sideways, or any other direction than forward?

It is, you lock the direction but can have the camera any angle after you've locked direction.

gnirtS Posted at 2018-9-16 03:58
It is, you lock the direction but can have the camera any angle after you've locked direction.

Exactly.
Here is a quick tutorial on that

Hi, thanks for reaching us here in DJI Forum. We do appreciate bringing this query to us. For more of guided information, please visit our official YouTube channel. Thank you.
https://www.youtube.com/playlist?list=PL8-vxWY64sBOZVVeCqtTx6OIeyofq_Ver

And just as a tip from someone who made the mistake... don't move the camera once you've started the Hyperlapse, it doesn't produce very good results. I wasted a 25-minute flight making a 25-second Hyperlapse that was nausea-inducing.

So far Waypoint HL has been very frustrating.   Once i set an initial WP the app is very restrictive of how much I can change the orientation of the camera and gimbal between shots.   Constant messages about too big or too little of a change between them.  Won't let you set the next WP until you conform to its hidden logic of what is a correct amount of change between WPs.  This results is a time consuming, frustrating and ultimately useless experience.