Thanks for your question! We're currently in between projects and while we'll never use Unity, switching to open source without a dedicated in-house engineer is pretty out of our future. But there's definitely a regular conversation in-house about engines and where we want to invest in development.
About your Steam Deck and Linux question: even though we haven't yet received official verification from Valve for Steam Deck compatibility, many of our fans have reported that Hill Agency runs smoothly on their Steam Deck. However, at the moment, we don't have the resources to port it to Linux.