If you use the pointer lock, the v-angle will be automatically changed. But you said you want to limit the v-angle?

If you want it to move freely but within a range, you can still use the same block to set the v-angle whenever it is outside the range.

This seems very similar to the Minecraft demo, where you use “lock pointer” to control the camera view using the mouse pointer:

play.creaticode.com/projects/660aa865b57a3da838c387bc

 
To lock the vertical angle, a simple trick is to repeatedly set the camera’s v-angle to 90 degrees whenever it is not: