I haven't interacted with Tropic Square in any capacity nor do I think it has been an idea to use in a GrapheneOS device simply because there's no largely available 'product' and there would be a lot of developer work. I don't know about other team members interactions.

ATM our expectation is Qualcomm is going to add MTE to Snapdragon this year and OEMs willing to provide timely patches would mean a lot more devices would be meeting our standards in 2026. We're in contact with an OEM to make a GrapheneOS variant of a phone with a next generation Snapdragon flagship that can hopefully come in the coming years.

Snapdragon flagships have a basic secure element, but it wouldn't be as secure as the Titan M2, but it is sufficient at a baseline. This is the most likely alternative for the next non-Pixel GrapheneOS device. Snapdragon does other things better outside of secure element though.