Adapting Affinity Designer to Linux (Ubuntu would be a great start) is not only about gaining popularity among Linux users but also among users of other platforms. Lot of Universities are using Linux on their workstations, and most students have absolutely no idea about graphic design or vector editing software until someone at university shows them. From experience, they either go for an open source alternative (Inkscape), or for Illustrator because most Universities (where I worked) had licenses. Meaning that the students are now aware mainly of these two software. Promoting Affinity on Linux could increase the use in the Academic field (because both Linux and Windows users would then use it to collaborate) and, by extension, the use among students.