I have a SOP with one or more animated xforms inside. How do I constrain another object to that motion?

I can use the Fetch SOP but it doesnt seem to work with xform animations.

Try a rivet or a sticky object and parent to that.

I think I'm a bit too stupid for these tools. I imported a camera via collada fomat and it's nested in all kinds of subnets with animations attached to it.

I want my standard Houdini camera to be perfectly aligned with the imported camera…

use the Fetch operator at OBJ level, and parent a camera to that one

Related: How would I get the motion from an outside object copied to a delete SOP? (from an object inside multiple nested and animated subnets etc)

if you are trying to grab world space transforms from any object and apply them to xform SOP you can use origin() expression for that