I will note that full nativization didn’t work until 4.20 because the engine had several bugs blocking it with the interface when manually implemented on an object (partial nativization worked but that is a pain). I got a bunch of them reported in early previews and it nativizes fine in 4.20 now (for me, you seem to be on 4.20). That error is about auto generated code headers not having PragmaOnce which is kind of out of my control and I don’t get it when I nativize, you might want to try clearing your intermediate folders and regenerating the project before trying again.
As for “hard to hit 90fps due to ticks”, are you on mobile? I can’t imagine that being the case on any other platform, the template is not CPU limited and most things don’t tick unless interacted with (hands, camera, pawn aside). Did you actually profile that CPU was the issue for you?