It’s possible for non-root users to talk to Incus and control it, either fully (members of the incus-admin group) or in a restricted fashion (members of the incus group).
But Incus itself will always run as root as it needs to perform a bunch of privileged actions like generating security profiles, handling filesystem operations, preparing network, …
So at the end of the day, only the allocation for the root user matters to what Incus does.