The trickiest part is that it starts about two notes from its bottom. Most songs start around the middle of their range. If you try that with the Star Spangled Banner you’ll hurt yourself when you try to get up to the “rockets red glare”.
I used to be able to sing it, when I was young. I simply used an arrangement that suited my voice.
Now, because I strained my singing “muscles” too many times, can’t sing worth beans. Strained my achilles tendons and ham strings too many times, and can’t even run.