I don’t think it’s possible, unless you use streaming levels system.
The thing is, actors are attached to World, which is usually the level, so it can’t persist without it.
Game Instance is an Object (parent class of an Actor) so it has no World connection, that’s why it can persist between levels.
If you use Streaming Levels, then you can add your Actor to Persistent level which is never unloaded and your Actor never will as well.
If you switch levels with “Open Level” node, then I would try to convert my actor to a base Object and spawn it on begin play of Game Instance. I think - but I’m not sure! - if you set Outer of the new object to Game Instance it will stay alive until you destroy the game instance.