If Proton could partner with Signal so that both customer bases could communicate with each other with messaging, voice, and video. One of the biggest limitations with private messaging is whether or not the people you want to communicate with have the same technology. Expanding the customer base would benefit the customers of both groups. Signal has a mature product running on all of the major platforms. Proton could offer international hosting, which would limit government throttling like we've recently seen with Telegram. It would seem like Signal and Proton could find common ground that benefits both of them and their customers.