One of the main purposes of these chips and the entropy they generate is to protect the keys on it from remote attacks. The moment your hardware wallet lands in someone else's hands is the moment you should start setting up and moving your keys somewhere else. It doesn't matter what chip in on the device that holds the keys. Look at it as a bomb waiting to explode. Before it does, get away from it.
The Tropic01 chip is not open source as, unlike software, you cannot simply compile your own binary (hardware). Using "open source" in the context of hardware is misleading imo.
No chip is open-source. Tropic Square's chip is different from competitors in that you don't need to sign an NDA to use it. You are also free to discuss and report on bugs, a topic that is more complicated for hardware protected by NDAs.