The pagy pagination gem is quite popular, and calls out Mongoid directly (see https://ddnexus.github.io/pagy/docs/api/backend/).

Though there are non-AR implementation how-tos (ex: https://github.com/ddnexus/pagy/blob/master/docs/how-to.md#paginate-non-activerecord-collections) and an existing "Extra" (see https://rubygems.org/gems/pagy_mongoid_cursor) for Mongoid, this is something we should investigate/document/promote for greater awareness.