Assuming I understand your question, no the implementation can be different as long as the consensus rules are followed. The only thing is that if you have lots of competing implementations, I believe...
Yup which is why knots is pretty much perfect for this use case since it is basically core and has been maintained right alongside it for the majority of core’s existence yet @ODELL is frustrated by knots for some reason… so I was wondering if he’d consider using something like btcd… but I don’t think he would for the reasons you mentioned.