Can I set a typoscript lib depending on the presence of a register value?

I have the task, to display a certain breadcrumb path if a special register value is set. I tried to access these register-values directly in fluid but they seem not to be evaluatable (conditions with f.eg "greater than" dont work at all) So I came up with probably a TS-lib and I tried the blow TS. Can you see, what I want to do ? Is it possible to set "lib.defaultproductpath to 1 or 0 depending of that register value ?:

# die Anzeige des default-product path an/aus schalten
    
    lib.defaultproductpath = TEXT
    lib.defaultproductpath.value = 1
    lib.defaultproductpath.if {
         10 = TEXT
         10.data = register:level1-uid
        // isGreaterThan
    }

I assume:
register:level1-uid = 0 => return 0
register:level1-uid > 0 => return 1

multiple option:

lib.defaultproductpath = TEXT
lib.defaultproductpath {
   value = 0
   override = 1
   override.if.isTrue.data = register:level1-uid
}

lib.defaultproductpath2 = TEXT
lib.defaultproductpath2 {
   value = 1
   override = 0
   override.if.isFalse.data = register:level1-uid
}

lib.defaultproductpath3 = TEXT
lib.defaultproductpath3 {
   value = 1
   override = 0
   override.if {
      equals = 0
      value.data = register:level1-uid
   }
}

lib.defaultproductpath4 = TEXT
lib.defaultproductpath4 {
   value = 0
   override = 1
   override.if {
      isGreaterThan.data = register:level1-uid
      value = 0
   }
}

This result in different values if register:level1-uid < 0!