Having a Game Boy Advance SP and a GameCube with a Game Boy Player is a lot like owning a Nintendo Switch, except that you already have hundreds of good games to choose from and there's no update patches to download.
The trade off of course is that your games display in standard definition rather than 720p, but at least you can get paper instruction manuals for them and the cartridges do taste much better if you start feeling a little chompy.
You do need to worry about SP's original battery going bad. Original SP batteries are 10 to 15 years old now and replacement batteries are Chinese junk that may only last 10 minutes before going up in fire.