When one talks about sovereign solutions for collaboration, the main things coming to mind are data ownership, often going hand in hand with data security, especially in a governmental context, and lack of vendor lock-in. Open-source software is a great way to achieve this sovereignty. However the fact that a lot of the collaboration happens cross-organisation is most of the time overlooked, with discussions falling back to email. However the boundaries of an organisation should not limit modern collaboration! But how do you solve the political problem of “shall we chat on your platform or mine?”, in particular in a cross-country context. Open standards, like Matrix are the key here, from simplifying the user experience via OIDC login, to the true sovereignty of owning your share of your conversations’ data.