The absolute low-tech solution would be to dedicate a switch for it.
If you have decent infrastructure with a managed switch, you can easily create a VLAN.
Besides the fact that the female RJ45 is usually inside the dwelling. You'd have to unmount the camera, pull out the cables and connect to it, all at typical heights of 6' and above. That's maybe a concern in commercial setups, although then we're circling back to VLAN.
As a more general rant - people who have maybe used 5% of the feature set of C++ come along and explain why language X is superior because it has feature Y and Z.
News flash, C++ has every conceivable feature, it's the reason why it is so unwieldy. But you can even plug in a fucking GC if you so desire. Let alone stuff like basic meta programming.
These libraries already exist. God how people underestimate C++ all the time.
Of course you can use a unit type that handles conversions AND mathematical operations. Feet to meter cubed and you get m³, and the library will throw a compile error if you try to assign it to anything it doesn't work with (liters would be fine, for example)
There's several libraries, including some supporting units and mathematical operations yielding the correct result types.
And as usual, it mostly comes with zero overhead, beyond optional runtime range checking and unit conversions.
But C++ is a meta-programming language. Making up your own types with full operator overloading and implicit and explicit conversions is rather easy.
And the ADA feature of automatically selecting a suitable type under the hood isn't actually that useful, since computers don't really handle that many basic types on a hardware level. (And just to be clear, C++ templates can do the same either way)
It's funny that you mention IPSec, since that would have made most of the application-level encryption we see today obsolete. They did have good intentions, and if it was widely accepted, it would have meant that barely any applications would have had to deal with the details of encryption, including the ever-looming possibility of doing it wrong (doing encryption right is hard!).
Now we have a slew of protocols that either implement TLS, or roll their own custom thing, or have X-over-HTTPS protocols, including SSTP and DoH.
The absolute low-tech solution would be to dedicate a switch for it.
If you have decent infrastructure with a managed switch, you can easily create a VLAN.
Besides the fact that the female RJ45 is usually inside the dwelling. You'd have to unmount the camera, pull out the cables and connect to it, all at typical heights of 6' and above. That's maybe a concern in commercial setups, although then we're circling back to VLAN.