This is a healthy thing to happen to the Linux browser ecosystem imho.
We talk a lot about browser diversity, but on Linux and Windows, it is a lie. You have firefox (gecko) and fifty flavors of chromium. Webkit on Linux has essentially been relegated to embedded devices or the GNOME epiphany browser, which I'll admit while is a noble effort, lags a bit in the stability and power-user features department. Big reason for that is that it lacks the commercial backing to keep up with the modern web standards rat race.
Kagi bringing orion to Linux changes the calculus. It introduces a third commercially incentivized, consumer-grade engine to the platform. Even if you never use orion, you want this to succeed because it forces WebKitGTK upstream to get better, which benefits the entire open source ecosystem.
The sticking point like always will be media playback (read: DRM/widevine). That is the graveyard where Linux browsers go to die. If Kagi can legally and technically solve the widevine integration on a non-standard Linux webkit build, they win. If not, it will be a secondary browser.