Hey thanks a lot! Sorry I'm slow to reply, I've been super busy and I often don't think to check itch.
I'm not sure I'm the best person to ask about scaling, I have been doing more responsive design than scaling in my own projects. Even my video (which does have some mistakes as I have since learned) is more about responsive design. I really need to update it. Better than my video: Pixelated Pope's video series on scaling and resolution. It's a bit old and is meant for Game Maker Studio and of course not everything will apply, but it has a lot of information and maths that can be creatively adapted to work with the event system in GDevelop.