Find and submit the guitar rig, amplifier setup, effects pedalboard, software, keyboards, studio equipment, headphones, DAW & software, plugins, and other instruments used by Ossian.
If the artist is active on social media, check places like their Instagram feed and look for musical equipment they can be seen using.
You should also do a Google image search for things like "Ossian studio" and "Ossian live" and spot gear that way.