Don’t worry about asking, Aaron! We are always ready to help!.
Regarding your questions.
You can create a new Sheet to store this “gallery”, each row will contain the owner of the image and the image link itself. Populate it with a form, using an image picker and a “signed-in user’s email” special value.
Add a “public” boolean column in the Sheet above and let users choose whether to make their image public.
Create an inline list, let’s say “Your gallery”. This will be a relation from the user profiles sheet to the Gallery sheet using the email to connect them together.
The “Public gallery” is another inline list where you can just point it to the Gallery sheet and filter by “Public” is true.