Adding a prop to an NLA Track or adding NLA track to a prop

Does anyone knows if it’s possible to add a property to an NLA track which is not just a ‘read only’ property but actually a property that I could later use?
for example of I write
bpy.types.NlaStrip.register= bpy.props.BoolProperty()
then this “register” property is just read only and doesnt really have any use.

If not, then is it possible to add an nla track or a strip’s “address” or “ID” (and not just the its name or some property value) into a custom property that is stored in the file?

Thanks for any help