"something that comes close to a fixed blade knife, even in terms of lateral strength (eg. prying) ", "off the shelf"? None.

Even a very strong semi custom like a Chris Reeve Sebenza is going to loosen eventually with lateral prying. That is something some fixed blades do not do well.

Take prying out of the equation and I'd go with a Sebenza's framelock or an axis lock such as that on The RSK Mk1 and many other Benchmade knives. It's a very strong lock.