Gematsu's daily Steam update notes that Last Harbor will ship with both Online PvP and Online Co-op — a first for tinyBuild's survival lineup. Previous tinyBuild survival titles (Raft, Valheim publishing) have leaned toward PvE co-op.
The PvP flag has not yet been confirmed as a launch-day feature, but the Steam store page now lists it under the multiplayer category, suggesting it is part of the launch scope.
Source: Gematsu.