For developing a browser on Linux, I highly recommend considering Igalia. They are an open source consultancy with extensive experience in browser technologies. Notably, they developed WPE WebKit, an optimized version of WebKit for embedded systems. Their expertise in web engines and contributions to major browser projects make them an excellent choice for your Linux browser development needs.
If you contact them you can get an estimated budget to give you an idea of how much it might cost to create a version of Orion for Linux.
https://www.igalia.com/contact/
https://www.igalia.com/technology/browsers
https://wpewebkit.org/