I tested WAFs in the past, also ones from the big players and while they might block some cheesy stuff on the application layer, as long as they are not heavily tailored towards your application, they stop bein effective against most manual stuff.
Everything lower than application layer ist not a WAF btw, so I am not sure if you mean WAF or some Firewallish stuff.
Just stick to best practices and expose only what you really need to expose. When putting third parties in front of your stuff this als has data protection implications. If using it makes you feel better okay but it should not feel you more secure if you expose vulnerable stuff.
You wrote:
there’s certainly plenty of implementations which i wouldn’t class as obscurity.
without specifying further. How am I supposed to work out what you mean? I did a guess in my last answer and you seem not to care about a discussion on the topic but instead now question me. I
I just wanted to make clear that port knocking is obscurity and maintaining and configuring your still public facing services in a secure manner is essential. There are best practices which I did not define and are applicable here.
If you whitelist your IP that of course helps but I am not sure what that has to do with port knocking. Whitelisting an IP after it knocked right, that would be obscurity. Whitelisting an IP after it authenticated through a secure connection with secure credentials? Why not just use VPN?
I am also not directly commenting on OPs question, as I try to tackle missconceptions in the comments.