Ok, I've read through the first 6 chapters of
https://www.debian.org/doc/manuals/maint-guide/
Great! It's a lot of reading but it'll help make everything else make more sense.
I an "upstream author" and "upstream maintainer" and maybe I'm looking
for a "maintainer" (the person making the Debian package of the program)
Is that a thing? When I was first looking into this everything said I
needed a sponsor. Are there people who are just maintainers and will
take my software and package it?
Yes and yes.... But, there are relatively few of us and we're all really busy. Someone MIGHT love your game and want to take the time to package it but, to be blunt, there are quite a few awesome games out there and not enough maintainers to package/maintain all of them. If you really want your game in Debian then the best way is to do the Debian maintaining yourself. If you find a good sponsor and get a feel for the packaging workflow, it will become very easy. And much more quickly than you might think right now. ;)
So, I would assume I would create a pck file of the game, make
godot3-runner a dependencies, then I would just need to create an icon,
desktop file, and a shell script that would tie it all together and tell
godot3-runner to run my pck file.
I'm not sure. Learning more about Godot is high on my to-do list but I haven't gotten to it yet. I'm sure someone on here knows more about that. I'd check the debian/changelog file for the Debian Godot packages if you want specific names of knowledgeable people.
I really want to get this down. I have lots of plans for games and would
love to see them in the debian repositories.
You've found the right community here for advice and encouragement. Good luck! :)
-Olek