Given how important this problem is to solve I would advise anyone with a credible solution to shout it from the rooftops and then make a ton of money out of the resulting customers.
I believe you've covered some working solutions in your presentation. They limit LLMs to providing information/summaries and taking tightly curated actions.
There are currently no fully general solutions to data exfiltration, so things like local agents or computer use/interaction will require new solutions.
My personal perspective is that the best we can do is build secure frameworks that LLMs can operate within, carefully controlling their inputs and interactions with untrusted third party components. There will not be inherent LLM safety precautions until we are well into superintelligence, and even those may not be applicable across agents with different levels of superintelligence. Deception/prompt injection as offense will always beat defense.
Find the smallest secret you can't have stolen, calculate the minimum number of bits to represent it, and block any LLM output that has enough entropy to hold it. :P
These opinions are my own blah blah blah